I use script runner built in script to change ownership of a filter.
If you don`t have it you could user the user switcher plugin to impersonate another user and chage the filter ownership this way. (https://marketplace.atlassian.com/plugins/com.tngtech.jira.plugins.schizophrenia) ---it's free ;)
Working on this particular issue, thankfully only for one filter/subscription at this time.
A workaround is:
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