I came across this problem and answer, try this one https://community.mendix.com/link/questions/104915
This is the exact answer in the forum:
- In Project > Settings > Configuration > Server > Root URL: http://{appname}:{portnumber} (make up different appname and port number per project)
- In your hosts file in C:\Windows\System32\drivers\etc add the different appnames with local ip address like so:
127.0.0.1 appname_1
127.0.0.1 appname_2
127.0.0.1 appname_3
Now you can run all the different apps and view them within the same brower (in tabs) without having issues with the sessions.
Props to Sjors Schultz