This bug was impacting the Edit Operation when it was performed in legacy mode (<hostName>/secure/EditIssue) : the save is not performed without error logged.
If you are using Minyaa 3.4.3 to 3.5.1 with JIRA 6.3 to 6.4.12, the Legacy Edit Issue operation does not save your modification.
It has not impact on Create Operation (Legacy and Popup modes), nor in Edit Popup and Inline modes.
It may also concern the modiication iniated by Version Merge.