I saw this thread and noticed that no one has posted any solution. So here we go…
I had the same issue with the Micro SD card that I bought. It’s the 128GB Samsung Evo Plus micro SDXC UHS-1 Class 10 with max speed rating of 130MB/s.
Note that it is important that it is an SDXC UHS-1 type, because SDXC UHS-2 and UHS-3 are not supported. It said on Eufy web site.
The SD card I bought failed to format inside my Eufy 360 pan & tilt indoor camera. Tried a few times and the formatting kept failing.
I then took the card out and format it using my PC using the exFAT format.
After that, I stick the SD card back into my Eufy camera. The Eufy app asked me to format the card again. This time, Eufy was able to format the SD card successfully.
Tested and the card works well recording and playing back the recorded videos.
I hope this helps.
Asfen