Can't switch to JQL Basic mode when username is uppercase

Summary

Can not switch to basic issue navigator view when an upper case name is entered in a JQL query.

Steps to reproduce

1. Create a new user as "NONADMIN"
2. Search for the username using the following JQL query:

   assignee = NONADMIN
   

3. Can't switch back to Basic mode:
   

Expected Results.

You are able to switch to Basic mode.

Actual Results.

You are prevented from switching into Basic mode.

Notes

The general issue is that queries for assigne="UPPER_CASE_USER_NAME" trick the issue navigator into thinking it is a complex query. You can reproduce this issue with any username.

Workaround

You can simply type

assignee = nonadmin

and you should get equivalent results. Username searches are case-insensitive.