Beatstep Pro Reaper Loop Glitch?

[Ka5par]

Anybody here use REAPER with Beatstep pro?

Does anybody know if it's a known Beatstep pro / REAPER issue or are there any settings that could help?

When I play loop selection in Reaper and Beatstep is synced via USB, then the playback always stutters or skips at the beginning of the loop.
At the beginning of each loop the cursor shifts a bit forward from the bar line position, also when clicking on another bar.
Occasionally the tempo reading on the Beatstep goes from the project tempo 150bpm to 149bpm.
If I start recording audio on another track while Beatstep is synced, I get a very short audio item, about the length that the cursor skips forward in the video.

Here's a video with sound:
https://www.dropbox.com/s/p8mfhcpsem356xe/Beatstep_Loop_Sync_2021-04-02%2021-14-32.mkv?dl=0

These are the MIDI in out settings:
https://imgur.com/2V20ot3

OS - Windows 10.
For testing purposes I'm using the latest REAPER fresh portable install.

[Ka5par]

I've troubleshooted the problem on the Facebook group also and here are the latest findings.

1. I tested it on another computer - a 2011 Macbook Pro - the exact same result.

2. Then I did a reset on the Beatstep pro - same as before.

3. If I disable the control messages on the input, the skip/stutter problem goes away, but then the playback buttons obviously don't work.

4. I also get frequent MIDI note hangs with the Beatstep sync set to USB, otherwise not.

5. If I choose a specific channel for the input control messages, then the stutter resolves, tempo is in sync, but transport controls don't work and the first note of the loop is missed.

6. If I choose noSPP in the MIDI output, then I don't get No skip/stutter, but the DAW play/stop control becomes glitchy - edit cursor skips forward with each play/stop and needs to be clicked very shortly to start playback.

https://imgur.com/4ULkjvD

7. The note hangs don't happen if I insert a MIDI Note Sanitizer JS plugin in front of a synth plugin.

8. The short recording problem still persists - now even shorter - the recording stops immediately after I press record and get prompted to save the microscopic wave or MIDI file.

So, I sort of got workaround for the original issue, but it's still broken for some reason.