To anyone affected by the internal storage formatting issue (in this topic @Federico_Iadarola @Tschulius @brianleach @magoo @AnnaTreurniet):
Fairphone can’t reproduce this bug. Therefore, if you want them to work on it, please #contactsupport specifying in the subject: “A10 - SD card phone storage issue”, precising which SD-card model you own. The more data they will have, the better they will be able to work on it 
Can you also all confirm you are on the latest build of FPOS? If not, could you please update and try again?