It could potentially be the newest BSG patch that is cocking everything up but the downgrade patcher was updated yesterday so I'm not quite sure to be honest.
Here's my recommendation for you RBizzle and I know doing all of this again sucks but it will work in the end:
To start off, make sure you find and delete any trace of SPT so you are starting a fresh clean install. Download the latest downgrade patcher for 0.14.0.2.28784 here >> Downgrade Patcher > then copy and paste all of your Live Tarkov's files in to a new folder called SPT 3.7.6 for example > then extract the contents from the downgrade patcher in to your SPT folder > start the patcher, once the patcher has finished doing it's thing remove the patcher.exe file and then add AKI version 3.7.6 and it should work as intended.
I do believe the Patcher isn't transferring all of the necessary files over for some odd reason but doing it manually like I've suggested at least then you know that all of Tarkov's files and data has been copied and pasted over for SPT so it should work.
If for what ever reason it doesn't feel free to update here and we'll go from there. Hope this helps.