Problem with save file on mobile devices

[Schnida]

System: PS Vita
Version: ​https://www.scummvm.org/frs/scummvm/2.1.1/scummvm-2.1.1-vita.vpk
The same problem occurs on the latest nightly version (psp2-master-19fe3521)

Game: Putt-Putt Enters the Race (German Version from Steam)

Problem
When I try to save the game with the in-game load and save interface this error pops up: "Failed to load saved game from file: puttrace-de-Töff-Töff.sg1"
I went to the save folder and found a file called "puttrace-de-temp.sgS".

Observations
I tried to save the game on other devices I own. The results are the following:

• Windows 10 -> Saving works
• 3DS -> Saving doesn't work (same error)
• PSP -> Saving doesn't work (same error)

Interestingly, the English version of the game works just fine on every device, which lead me to believe that the umlaut in "Töff-Töff" might be the problem.

Thanks for taking your time. I hope I didn't leave out any important information.

[Schnida]

This file is created in the save folder after the error message pops up. It works on Windows when I rename it btw.