Due to the lack of support from Virtuali, I did some research and came up with a TEMPORARY SOLUTION, THAT I HOPE VIRTUALI FIXES IT AS SOON AS POSSIBLE IN THEIR NEXT UPDATE. Here it goes: Go to your "Prepar3D Add-ons folder", then to "FsDreamTeam Addon Manager" and open "add-on.xml" with WordPad. On the last category ("EXE"), where you have <Path>F:\Addon Manager\couatl64\couatl64_P3D.exe</Path> ("F:" is the disk where my FSDT Addon manager is installed, yours may be different!!)
, edit this line to <Path>F:\Addon Manager\couatl\Couatl.exe</Path>. Apparently everything works fine after I did that...