Jira Issue picker customfield giving error searching when given correct values

[Michael H]

I have an issue which has issue pickers as its custom fields. When I try to select an issue for each issue picker, typing in a value that would correspond to the 'fields to search' doesn't work most of the time. An example of an error I got is as follows: java.lang.IllegalStateException: field 'customfield_11217" was indexedwithout position data; cannot run PhraseQuery (phrase=customfield_11217: 'backlog test'). Interestingly whenever I type the word test into the issue picker search, some but not all issues with the word test would appear. If someone can explain what is causing this that would be great