Many thanks,
The problem is updating to beta 11.1, it did indeed work fine on 11.01 release.
I will wait till the next release, currently there are a few other things not working quite right apart from teenysduino, I...
The latest big sur 11.1 update doesn't load the teensyloader, it's also still crashing when opening arduino, but works on reload..it was doing this before but now as i said won't lode the loader?
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