Running Renoise 3.1 x64. Plugins in Sandboxes. I haven't been able to test this as thoroughly as I'd like as I only have one plugin that sends MIDI signals, an arpeggiator, but here goes...
Switching from ASIO to Directsound, there's a noticeable delay in signals coming out of the arpeggiator, resulting in a swing effect and desynchronisation with the rest of the song. I assume this is because of the increase in latency with Directsound (it's around 150ms, with ASIO at 21ms)?
When I loop a region in the pattern sequencer, after the region has looped once, the signals coming out of some instances of the arpeggiator are bugged, leading to what I can only describe as a chiptune like effect (seems notes are being triggered much faster than they are supposed to be). Interestingly this doesn't happen when I loop the pattern using the transport or if the song reaches the end and loops back around, only when I set a region in the pattern sequencer.
Both these bugs I can reproduce 100% of the time. Unfortunately I can't attach an example as I'm using commercial plugins but I can upload a video if that'd help.