OK, sorry, noticed this bug report just now.
vimode in 1.38 is quite broken because of the problems described in https://github.com/geany/geany-plugins/issues/1136 (which I think I fixed in #1141 and #1139 but these haven't been merged yet).
The problem with the visual mode is new to me (unless by "visual mode" you actually mean "command mode" in which case it's the numlock-related problem that should be fixed by #1141). I seem to be able to enter visual mode from the command mode by `v` without any problem.