I had the same issue. I think at some point after converting the SD card to adoptable storage, I noticed a decrease in the amount of Internal Storage. I incorrectly assumed that using the "migrate data" feature found after pressing the "more" button in the internal storage area of the settings (settings>storage>internal storage>more>migrate data) would move data from internal storage to the adoptable storage on the SD card. This is WRONG. This action moves data from the SD card to the onboard internal memory.
How I fixed the internal storage insufficient issue:
1. Back up data to a computer using Samsung Smart Switch (
https://forums.androidcentral.com/e...%2Fowners%2Fapp%2Fsmart-switch&token=EpoCgGCd) This took about 1.5 hours to complete for a total of about 60 GB of data.
2. Convert the SD Card to Portable Storage (settings>storage>SD card>more>format as portable storage). This will move as much data as possible to the on-board memory and format the SD card to portable storage.
3. Follow all of the steps to re-convert the SD Card back to Adoptable Storage. This link was very useful because a video accompanies the instructions. (
https://www.xda-developers.com/enable-adoptable-storage-for-galaxy-s7-and-s7-edge/)
Note - the updated ADB has global access, so when using the "administrator" command prompt, it is unnecessary to type in a path for the location of the ADB program.
4. VERY IMPORTANT - After formatting the SD Card as outlined above, do not forget to use the "migrate" function for the SD Card (settings>storage>SD card>more>migrate data). This will move data from the on-board memory to the adoptable storage memory card. YOU CAN ONLY DO THIS ONCE AFTER FORMATTING THE SD CARD TO ADOPTABLE STORAGE.
5. Use Samsung Smart Switch to restore all of you data (takes about 1.5 hours).
Following this process released 12 GB of "internal" storage and allowed me to update all of my apps and install new apps. It appears that the "internal storage" might again accumulate. At that time, I plan to repeat the process. I hope the next phone just comes with a larger solid state drive, like the I-Phone. I would rather pay more to have accessible, reliable data access.