JQL search with 25 keys vs 26 keys results in different behavior when an issue doesn't exist

Issue Summary

When a customer uses a JQL search where some issues don't exist, the result is different if they have more than 25 issue keys.

Steps to Reproduce

Step 1
Create a JQL query with 25 keys
Make sure that at least one of the issue keys does not exist.
Example: This query has 25 Keys. PROJ-88 doesn't exist. 
key in (PROJ-1, PROJ-2, PROJ-3, PROJ-4, PROJ-5, PROJ-6, PROJ-7, PROJ-8, PROJ-9, PROJ-10, PROJ-11, PROJ-12, PROJ-13, PROJ-14, PROJ-15, PROJ-16, PROJ-17, PROJ-18, PROJ-19, PROJ-20, PROJ-21, PROJ-22, PROJ-23, PROJ-24, PROJ-88)
Results of Query

No results are returned and an error is shown.

Step 2

Create a JQL query with 26 keys or more.
Make sure that at least one of the issue keys does not exist.
Example: This query has 26 Keys. PROJ-88 doesn't exist. 
key in (PROJ-1, PROJ-2, PROJ-3, PROJ-4, PROJ-5, PROJ-6, PROJ-7, PROJ-8, PROJ-9, PROJ-10, PROJ-11, PROJ-12, PROJ-13, PROJ-14, PROJ-15, PROJ-16, PROJ-17, PROJ-18, PROJ-19, PROJ-20, PROJ-21, PROJ-22, PROJ-23, PROJ-24, PROJ-25, PROJ-88)
Results of Query

No error is shown and all results are returned except those that don't exist.

Expected Results

JQL searches should be consistent regardless of how many keys are searched. Allow JQL searches with 25 keys or less to skip validation and show no error like searches with 26 keys or greater

Actual Results

An error is thrown if 25 keys or less are used in the search. If 26 or more keys are used an error is not shown. 
The customer would like no errors to show regardless of query size.

Related Suggestion Requests

(JRASERVER-40245) Allow JQL searches via the Issue Navigator to skip validation and return partial results
(JRASERVER-23287) Searching for an issue key that doesn't exist with JQL should not cause a query/validation error.

Workaround

If you don't want JQL to break when having an issue that doesn't exist, make the query longer than 25 keys. Issues that do exist will be returned and those that don't will be left out.