I was experiencing the same issue of no response from EFB.
As I had installed the MSFS beta on my development PC, lots of stuff was out of date.
After updating my FWB and GSX and removing FSLTL, the EFB now works fine.
(yes, I know it would have been better to retest after each so I would know which was the fix, but I was impatient)
Hope this helps someone 😉