In ProTracker, if the current sample number is empty (e.g. no sample data and no loop), and the sample number is changed to one with a loop, that sample should begin playing immediately from the start. If a sample is playing currently and the sample number is changed to an empty one, the current sample should first play all the way through before stopping entirely. That doesn't happen right now...
(this is the only behaviour that I'm aware of that isn't implemented yet - most of the other sample swapping quirks have been added)
In ProTracker, if the current sample number is empty (e.g. no sample data and no loop), and the sample number is changed to one with a loop, that sample should begin playing immediately from the start. If a sample is playing currently and the sample number is changed to an empty one, the current sample should first play all the way through before stopping entirely. That doesn't happen right now...
(this is the only behaviour that I'm aware of that isn't implemented yet - most of the other sample swapping quirks have been added)
See OpenMPT test module https://resources.openmpt.org/player_tests/mod/PTSwapEmpty.mod