I don't think it's a bug, but when setting a sample with a loop (sample loop or sustain loop), we are unable to offset the sample playback from any point PAST the loop start (playback will always start at the loop start point and stay within the loop). We often use breakbeats or long vocal waveforms and use different playback techniques to vary the sound, tempo, or accent. For example, if we have a sample that goes "O say can you see," we can set the loop at "say" to use different note sustains, but we can't then break the beat of the sample by using an offset for "can you see." Even if we pass the correct Offset command, MPT instead starts the playback at "see" and does not break out of that loop. In our case, we are using an instrument that hold several samples, so using envelopes will mean a complete overhaul of the sample setup, and is therefore undesirable. We have also tried a workaround by reversing the sample playback back and forth with the S9E/S9F commands, but this is undesirable because the tick to do a good reverse playback can't be specified, and there is a problem with audible clicks...

As requested, MPT should either ignore a loop if the offset call is beyond the loop end, or we need an Instrument control command which turns off a sample's loop. Perhaps S92 turns off the sample loop, S93 switches the sample loop to normal (unidirectional), and S94 switches the sample loop to Bidirectional -- these would be the equivalent of manually choosing one of these in the Sample page.