blackyet

Same, so clearly an FSUIPC 5 related issue

Similar here. But with a different sequence. Started with 747-400 variant, black screen, changed to mooney, changed back to 747-400 and it works... BUT it works only with the PMDG Livery of the 747-400 (the first one of the list to make it clear)

Tried 747-400F ...and back to square one with all black screens and so on

Some progress...removed all SimConnects, disable antivirus (Avast)...and the 747-400 works...testing other variants now

Tried to remove v3, but still nothing here. happy you solved it yourself

I have tried different ways. Removed all SDKs and simconnect installations and run everything again. In P3Dv3 works fine, which is suggesting it is not a SimConnect issue to me. Add-ons on P3Dv4 are FSUIPC 5, ORBX, A2A C172, ACTIVE SKY 2016 and off course PMDG 747

Same issue here. Win7/64bit P3D v3 and P3D v4 installed. Followed this (http://support.precisionmanuals.com/kb/a111/aircraft-loads-up-dead-no-activation-window-no-landing-gear-simconnect-issue.aspx SimConnect fix) but no changes. On v3 works well. No activation windows pop-up on v4