@taktik Oops! I have found it! A bug in Renoise 3.2.1 build 7 nov 2019 (Win10 Home)
When selecting a multi-column channel selection with the keyboard (shift) from left to right
The rightmost part does not get selected.
When I select the previous column, the selection also misses the right part.
I can replicate this bug.
create multiple columns on channel 2 and 3
navigate to channel 1
press shift - right until you see the selection miss the right part