Consider:
• The running App may be hidden behind the Kicad window (probably not but, worth checking)
• There are 3 or 4 different ways to run an External App from Python and a plugin. Using the “subprocess” method is the most-used, reliable way. But, you could try the “OS” approach - (change the necessary Path and App info):
os.system(‘/path_to_the_App/some_app’s.executable_file’)
Another Example - running a Java App:
subprocess.call([‘/usr/bin/open’,‘/Users/bruce/myJava_Out/Woof_R1.jar’])
Another Example - running a Windows App:
subprocess.call([‘/usr/bin/open’,‘/Users/bruce/Library/CopperCAM.exe’])
Another Example - running LibreOffice’s embedded DataBase App
subprocess.call([‘/usr/bin/open’,‘/Users/bruce/Documents/aDataBases/Project_Tracking1/Project_Tracking_1FORM.odt’])
Quick - test: Set the Path to Any App that works and try the OS approach (it may cause the App to keep running and/or close Kicad…) Machines/systems are not as smart as we think they should be…
You can Google around to find the others (probably quicker than my digging though stacks of paper)