Stutter when rendering with Reaper as Rewire slave

Hi there,

having an issue with 3.1 when rendering a song. The tracks are fed from Reaper via Rewire, the usual setup. Appears to play as expected, however when rendering the song, there appear to be short gaps in the final wave file just where the breaks are between the patterns. Meaning, when it goes from the 64th line in the previous patter to the 1st line in the next pattern, there would be a stutter in the render.

When that happens during rendering, Reaper flashes the time bar red which I understand signals buffer underflow. I tried to change the thread priority and various buffer settings in Reaper but that does not have any effect.

Those gaps appear in any render mode, realtime, offline, how and low priority. The problem does not appear to be present during regular playback, only during the rendering process. The issue does not affect rendering of regular renoise modules.

Any similar experiences or suggestions how to work around this?