I have a Mac running map version 2020.2 AND 2002.3
I can summarise the problem as follows:
If I create a fresh route A to B in 2020.2 I can switch and recalculate between 'Motorcycle' (a magenta line following roads, according to my preference settings) and say, 'Direct' (a straight magenta line A to B) at will, with absolutely no problems at all. I can go back and forth without a care in the world. But.....
If I then open the same route in 2020.3, I can switch it from 'Motorcycle' (magenta line follows the roads) into 'Direct' (straight line A to B) but I cannot then switch it back again; it stays as a straight line, no matter what I do. Nothing by way of recalculation or changing Activities will persuade it to be anything else but a straight line, A to B.
If I then go back into 2020.2 I can once more switch the same route between 'Motorcycle' and 'Direct' at will, the route alternating between conventional road following and a straight line, just as it should do.
In short, in 2020.3 once you get the straight line version of a route, you cannot then recalculate it (or do anything else) to get it back to a conventional route following the roads. The only way back is to switch back to 2002.2 maps.