If you are referring to the workaround given in the bugtracker … Clearing App data and/or cache is generic Android troubleshooting, so since Fairphone staff endorse it there it can’t hurt trying in this case I think.
Are you referring to the question in the last post of that bug?
Select Clear Data
will delete anything on the internal storage, won’t it?
Haven’t tried it, but clearing data for external storage surely won’t delete any data on the PC, right? Even more so since MTP doesn’t work…
And clearing the media storage data I guess only clears the indexed media information, i.e. the phone will have to re-index all media files.
At least in TWRP 3.2.3-0 MTP is enabled as soon as TWRP is started (and a possibly encrypted data partition is decrypted), else you can enable it in “Mount”.
You can boot TWRP 3.2.3-0 without flashing it … #twrpwoflashing.
If MTP works with TWRP, you could backup files from Internal Storage and the SD card (if there is any), and you would know the problem is most probably not on the PC side.
I hope this doesn’t sound like nitpicking, but of course clearing cache/data of an app will at least delete some files on the phone
Of course it’s better safe than sorry, but I just checked the app info of the two respective apps on my phone. External files uses 110kB and media storage uses 49MB. Clearing those surely doesn’t delete all files on the phone (around 20GB internal and 60GB on sd card).