Prestashop issues after upgrade

Experiencing issues after the following upgrades:
- Prestashop upgrade from 1.7.6.8 to 1.7.8.7
- PHP upgrade from 7.2 to 7.4
- Warehouse theme upgrade from 4.3.6 to 4.5.3

Issues:
Running the site in debug mode trows ContextErrorException on tools.php (Trying to get property 'id' of non-object). Might be important, might be nothing.

I heavily use the ordermanager module. This is having issues.

These are the symptoms I see:
- With ordermanager disabled, using two search criteria doesn't work in Prestashop orders. No selection is made and full list of orders is shown.
- With ordermanager disabled, still instant search is active (functionality of ordermanager)
- With ordermanager enabled, search only works with instant search enabled.
- With ordermanager enabled, search makes selection of orders but none of the orders can be opened since there is no link to click it open
- Having problems with my shipping module (myparcel) to show up with ordermanager enabled. I need to de-instal and reinstall myparcel for it to show up.

Test environment is provided.

Quick fix is needed. Only bid when confident you'll fix this fast.