Indeed, according to Jolla, and as seen on my Jolla 1 (waiting for the final release to upgrade my daily Xperia), they've switched away from their mout-sd.sh script and now use udiskctl (like almost every other GNU/Linux distro) to mount the SD card.

The SD cards aren't mounted into /media/sdcard/{UUID}, but in /run/media/{USERNAME=nemo}/{LABEL}. (There's only one loged-in user on sailfish, so the USERNAME part is always going to be nemo).

There's a symlink, so scripts search inside /media aren't completely lost.

But the path name has definitely changed (UUID vs LABEL, anyway), so Jolla tells you (and I can confirm) that you need to set the output path again in "Settings -> Apps -> Camera".

Probably that other apps will need new paths, too.
(Almost sure that OSM Scout server will need).

That seems weird. Have you ruled out partition corrurption ? What filesystem are your using on the card? (Fat32, exFAT + FUSE, ext4, btrfs/f2fs/udf ?)

For the record, it is not technically possible for Alien Dalvik to be anything more recent than Android 4.4 KitKat
As the name indicates, Myriad's software is an implementation of the Dalvik JIT-based JVM-like engine. That on is used up to 4.4 KitKat.
Starting from Android 5 Lollipop, Google switched to a completely different approach, "Android Runtime", with is AOT (Ahead of time: when a app is installed, the Java-like bytecode is compiled to native code) instead of using the JITting engine.

If Jolla wants Adroid 5+ in Sailfish OS 3, they'll probably switch to something else.
(Does Myriad have ART ? Has andbox progressed to the point that it can work nicely with most applications on Sailfish OS ?)

Any success while experimenting with it ?