Plugin readers - don't show readers list freeze at Loading table...

[Atlas Aerospace]

On one of the pages when I try to view Readers and their confirmations , in console I get Error: Failed to load resource: the server responded with a status of 500 at page (.../rest/readers/1/readersforpage/withlimit?pageid=29108089&limit=10&offset=0&_=1706564981575)
I tryed to add Confirmations to other page - all work fine and I can access and view readers in  table.  But I can't understand why I get error only on this page. 
Can anyone point me where to search for  problem resolution.
Readers for Confluence Ver: 1.2.7
Confluence Server 7.9.0

When I open link of 500 directly I see this StackTrace on screen:

<status>

<status-code>500</status-code>
<stack-trace>java.lang.NullPointerException at com.mht.confluence.plugin.readers.beans.ReaderElementBean.<init>(ReaderElementBean.java:166) at com.mht.confluence.plugin.readers.rest.RESTReadersForPage.getAllReadersForPageWithLimit(RESTReadersForPage.java:131) at jdk.internal.reflect.GeneratedMethodAccessor7585.invoke(Unknown Source) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.base/java.lang.reflect.Method.invoke(Unknown Source) at com.atlassian.plugins.rest.common.interceptor.impl.DispatchProviderHelper$ResponseOutInvoker.lambda$_dispatch$0(DispatchProviderHelper.java:181) at com.atlassian.plugins.rest.common.interceptor.impl.DispatchProviderHelper.lambda$invokeMethodWithInterceptors$0(DispatchProviderHelper.java:81) at com.atlassian.plugins.rest.common.interceptor.impl.DefaultMethodInvocation.invoke(DefaultMethodInvocation.java:53) at com.atlassian.plugins.rest.common.expand.interceptor.ExpandInterceptor.intercept(ExpandInterceptor.java:42) at com.atlassian.plugins.rest.common.interceptor.impl.DefaultMethodInvocation.invoke(DefaultMethodInvocation.java:53) at com.atlassian.plugins.rest.common.interceptor.impl.DispatchProviderHelper.invokeMethodWithInterceptors(DispatchProviderHelper.java:106) at com.atlassian.plugins.rest.common.interceptor.impl.DispatchProviderHelper$ResponseOutInvoker._dispatch(DispatchProviderHelper.java:180) at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75) at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84) at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542) at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409) at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:558) at com.atlassian.plugins.rest.module.RestDelegatingServletFilter$JerseyOsgiServletContainer.doFilter(RestDelegatingServletFilter.java:162) at com.sun.jersey.spi.container.servlet.ServletContainer.doFilter(ServletContainer.java:829) at com.atlassian.plugins.rest.module.RestDelegatingServletFilter.doFilter(RestDelegatingServletFilter.java:72) at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter(DelegatingPluginFilter.java:62) at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter(IteratingFilterChain.java:37) at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter(ServletFilterModuleContainerFilter.java:55) at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter(ServletFilterModuleContainerFilter.java:43) at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter(DelegatingPluginFilter.java:62) at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter(IteratingFilterChain.java:37) at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.lambda$doFilter$0(DelegatingPluginFilter.java:57) at com.atlassian.plugins.rest.module.servlet.RestServletUtilsUpdaterFilter.doFilterInternal(RestServletUtilsUpdaterFilter.java:23) at com.atlassian.plugins.rest.module.servlet.RestServletUtilsUpdaterFilter.doFilter(RestServletUtilsUpdaterFilter.java:35) at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter(DelegatingPluginFilter.java:62) at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter(IteratingFilterChain.java:37) at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.lambda$doFilter$0(DelegatingPluginFilter.java:57) at com.atlassian.applinks.core.rest.context.ContextFilter.doFilter(ContextFilter.java:24) at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter(DelegatingPluginFilter.java:62) at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter(IteratingFilterChain.java:37) at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.lambda$doFilter$0(DelegatingPluginFilter.java:57) at com.atlassian.applinks.core.rest.context.ContextFilter.doFilter(ContextFilter.java:24) at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter(DelegatingPluginFilter.java:62) at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter(IteratingFilterChain.java:37) at