Looping playback of a range hangs at start of the loop when speed is low.
The playback cursor hangs when it returns to the start of the loop range for the first or second time. Starting playback is normal. See the attached screenshot.
When I nudge the speed up a bit (e.g. +1 bpm) in the playback panel with the mouse wheel, playback continues the loop, until the next return.
Restarting the program won't help. When I let MS run in this situation, it dies silently after a minute or so. In the linux process monitor I see a constant i/o write rate.

Is not with all parts of the same song, but it is repeatable. Deleting measures before the problematic region won't help most time (i tried that a few months back in an other song).
It is related to the playback speed:
- happens each loop at bpm below 60,
- at bpm 60..65: each second loop, the first note does not sound correct (as in next point),
- 65..70 : the loop works normally, but some of the notes at the very start of the loop range are not played or sound staccato on each or each second loop.
- above 70: playback is normal
Having a (much) higher or lower default speed at the start of the songs has no influence.

In the attached song, it happens when using a play loop range for measures 17 .. 24. starting at 16, or 15+half, or 12, or ending at 22 or 21 won't help.
Playing loops with lines 1, 2, 1+2, 3, 4, 3+4 at low speeds were all normal.

The song contains a few hidden staves for bass, drums (also playing), claves (a click track, muted), and empty melody track (for a solo sax).

I encountered this problem for the first time when I upgraded from 1.(latest) to version 2.0 (Linux 64-bit appimage), Currently using v2.3.2 beta, (earlier v2.3 won' t run on my machine),
I enter my study songs myself using step mode input from a midi piano (hail to the new duration + repitch input modes), only the drum patterns are imported from a midi file (indirectly: patterns were once imported in a separate msc song, and copied from there to this song).

My system: Kubutu 18.04 linux 64-bit, kernel 4.15.0-39-lowlatency, using jack2 sound and midi backend, intel i7 cpu at 2.7 GHz, most times at fixed rate (having the cpu speed governor working has no influence)

I need these low speeds as I am using this as tool for my piano lessons. When I get to know the song better, I can use speeds above the problematic 65 bpm breakpoint.

Has someone a solution? Is this a bug?
Could it be left-over contents from an earlier-version MS song, as I tend to take a copy of a previous song with all the settings, clave/drum staves, and split piano staves as start for a new song after learing the piano contents.
In mean time I will export this song to a sequencer so that I can continue practicing this song.