Odroid C2 - SD-Card SMB-Share keeps getting deactivated

Hi

After updating to CoreELEC 9.2.1 the SMB share of my SD-Card gets deactivated almost each time i watch a video.
After rebooting it is still deactivated, but it gets accessible again after i toggle “Settings->CoreELEC->Services->Auto Share Exernal Drives” off and on.

CoreELEC is installed on a 16GB eMMC module and i use a 200GB SanDisk Ultra for storage.
The SMB shared folders on the eMMC stay available all the time, only the SD-Card share gets deactivated.
Up to 9.2.0 it ran perfectly stable.

Also, is it normal that SD-Card transfer speed is so slow (varies between 4-22 MiB/s, average way under 20 MiB/s) on the Odroid C2?
I used this SD-Card on a modded Nintendo Switch for some time and it held over 40 MiB/s when copying files onto it, and was also relatively fast when installing games onto it while it was source and target at the same time.

I really appreciate any help.