The following problems occurred:
The original SD card (Micro SD) still had 5 GB of remaining capacity; Maschine+ refused further expansion, even though it was only 1.2 GB in size. All previous expansions suddenly disappeared; Maschine+ displayed: "SD card unreadable."
Therefore, a 128 GB Sandisk Extreme V30 Micro SD card was purchased.
Formatted with Maschine+ and all expansions installed. Maschine+ worked for a while until a save process suddenly took noticeably longer; then the preview function stalled until the selection no longer responded; later, the display indicated that the SD card could not be read and needed to be formatted. The SD card was checked on the PC - Result: SD card OK.
Formatted again with Maschine+, installed the expansions. Maschine+ worked again for a while, then the same problems/error message. The PC could not read the SD card, indicating that the card needed to be formatted.
I've now ordered another, but "regular" SD card (not a micro SD card). I formatted and installed everything again. Since then, everything has been running smoothly (I hope it stays that way!).
Why does there seem to be a problem with micro SD cards, especially since NI itself ships with micro SD? Has anyone had the same/similar experience?