Read only SD card when using Seedvault

[Kamul-PL]

Hello, I've been using Seedvault with LineageOS for a few days now and I noticed, that my external SD card is read only since a few days also. I'm not 100% sure, that guilty is Seedvault, but I've made some research and here are my observations:

• I use the external SD card as my backup destination
• when I reboot my phone, the SD card is becoming writable again
• some time after next Seedvault activation the SD card is read only again (for test purposes I use manually triggered backups)
• it seems there's not such an effect if I use internal (emulated) SD card as a place for backups

My SD card (128 GB) is quite new (about 1 month), and not used much, so the hardware shouldn't be the problem. Does anyone have any ideas, what could that mean? Has anyone had a similar experience? Should I create an issue here?