I just sended you a teams invite for a meeting at 15:00 today afternoon.

Additional Info:

EVERY time i restart Unity its working fine, i NEVER got the "No Mutex" at the first startup of the playmode in Unity.

When retrying the second and third time exiting and entering the Playmode i encounter the No Mutex and it doesnt go away itsself(sometimes it does) but EVERY time i restart Unity the first time it just works as it should.

But restarting Unity everytime entering the playmode is just ridiculous

I deleted and replaced the .exe under 

"Assets\game4automation\private\Interfaces\PLCSimAdvanced\Ressources" 

so indeed you where correct that the exe was the false one.

I replaced your provided exe with the one under StreamingAssets but it seems that nothing changed. The NoMutex Error still appears after a succesfull startup.

The Editor log seems to be the same as before.

NewEditor.txt

Editor.txt

This is the Log file with Debug Mode enabled on the PLCSimAdvancedInterface GameObject and one startup of the Editor which resulted in the "No Mutex" error.

The error is still present on my end. 

I replaced the Coupler with the one you provided.

Here is a video of the Error happening:

NoMutex

Sadly im experiencing the exakt same problem.

It is not necessary tied to "first time it works and never again" - more a type of "i try it 20 times and then it suddenly works for one time again".

It is anoying as hell and interrupts the workflow massivly :-)

What i noticed:

The Coupler tries to restart the PLC in PLCSimAdvanced. If this fails(yellow light in PLCSA) then you get the NoMutex in the Couplers log. But when the coupler can start the PLC (green box in PLCSA) everything is working fine. 

When starting up the PLC manually in PLCSA it boots up without any problem, but ofcourse with the mutex in the console, it doesnt work afterwards.

Maybe the coupler doesnt start or verify the start of the PLC correctly?

Because i need it, i will take a look into downgrading......

Beside that, PLCSimAdvanced v4 is out for more than a year now, you should consider upgrading and supporting the newest version.

This is the PLCSimAdvanced 4.0 PLC Instance which was in the "Virutal Simatic Memory Card" of PLCSimAdvanced.

opcua.7z

Thanks for your help.