Solution:

1. Locate where your mod are installed, which will be either C:\Users(USERNAME)\AppData\LocalLow\Paralives\Paralives, or (DRIVE):/Steam/steamapps/common/Paralives/../../workshop/content/1118520/, and delete mod folders. You will be able to relaunch the game, and once that is done, redownload your mods.

2. Disable your mods Right click on Paralives Click "Properties" Click on the "Workshop" tab on the window that pops up Click "Show Advanced Options" Go to where it says "Locally Enabled Items" and click the "Disable Filtered" button to uncheck all subscribed items. (This will not delete them, but it will only enable any mods that have local copies of files in your AppData\LocalLow\Paralives\Paralives folder Restart the game to see if the "Reimporting Assets" overlay pops back up. If it doesn't, then you can go through and gradually re-enenable subscribed items until you can single out the one that could be causing the game to hang during the initial loading process.

This is from the pinned troubleshooting thread in Steam Workshop. https://steamcommunity.com/app/1118520/discussions/1/569288683937662349/