Reverted to 2018.3 and it worked perfectly right down to landing. So same route and this time in 2019.1 started off as before took off switched to Nav mode. Put on VS plane ascended got to preferred altitude and pressed ALT which activated but it didn't stop. I then thought it would ascend to Route Manager preset altitude in this case 4000ft. However it went past that and once again didn't stop then again no buttons worked.
It seems to be related to VS settings but why it works in 2018 version, and previously worked fine 2019 but appears to have changed since the last plane update. I am simply putting forward my thoughts.
As an aside the G5 doesn't switch on in 2018. Also Live weather still doesn't work in that version (perhaps an associated glitch). Unfortunately I uninstalled Josh's version so can't try that.