Tonebridge worked perfectly on my older iMac 2014.
It does not start on my new iMac 2021 (M1chip) Mac OS Big Sur.
I reported this problem several times since early june with screenshots en movies but I do not get an advice or a solution from Ultimate Guitar.
Outstanding app that has a myriad of pre set selections. It works very well and is easy to use. User input for additional setups are done through the http://ultimate-guitar.com site.
The fact that this little gem is free is quite amazing as I would gladly pay for it because it surpasses some of the paid apps I've bought for the Mac & iOS over the years. It is also available for iOS too!