Xzual, Thanks for taking the time to post! I'll need the complete log file with most issue posts. To attach log files that exceed the forum size limit for attachments, just compress to a .ZIP before attaching. Typical compression rates for log files exceed 90% so you should not have a problem even with log files from extremely long sessions.
The case above is an issue with using a trinket (
Nurong's Gun) that requires you to have a current enemy target and to be facing them. The original design for Singular trinket support appears to have been geared towards trinkets that buff your abilities, replenish your resources, break crowd control, or provide some benefit other than casting an attack on a current target. I'll take a look at adding support for that trinket type in a future release. For now to resolve this issue you will want to equip a different trinket that does not have that requirement, -OR- go to Singular Settings (click Class Config) and change the trinket usage for the slot it is equipped in to Never so you can still get the +mastery benefit from that one.
Thanks for the post and good luck with your Priest, Bobby53