When doing some testing for a noob via Teamviewer this evening I came across an odd issue. The version was 2021.29 so it may have been fixed since then.
The error process was as follows.
-I was testing a P10 matrix and was sending out a universe at a time to check the panel wiring and config. There was 3 lines assigned on the controller tab with 2 disabled and the 3rd line configured for the 75 universe P10 matrix.
-Changing to tools->test I ticked the "don't send data to unused outputs" as I wanted to confirm matching universes/channels etc from xlights to fpp.
-Unticked output to lights and went back to the sequencer tab, clicked on output lights and no data was being sent out to fpp.
-Changed back to tools>test, unticked the "don't send data to unused outputs", closed the test and the sequencer again worked as expected.