@ged click on offset in the bevel history node in the channel box, than drag mmb in the viewport, and or control+mmb to adjust the value in finer increments. this works for all attributes too. in the future im thinking of releasing some interactive tools i made, which bevel is one of them.
ya i had the same bug in early versions of my tools script but was able to work around it, and overall make thigns a little more stable, and better tied into maya's repeatLast and undo history. thinking i might quickly document my stuff and release on the weekend in it's current state.
I dont want to put you out, Im still learning maya so I havent ruled out using the default tools I just found those interactive extrude and bevel tools quite fast, unfortunately they seem to cause errors or crashes quite easily for example the undo history sometimes gets turned off if I mess up my interactive extrude :/
I like to put the quick keys for selection hiding and unhiding on my shelf. It makes it really fast and easy. Having delete history, freeze transformations, center pivot, and flip normals is really helpful as well. I use isolate selection a little bit, but it is only active in that one view port, the functions I showed…
Occasionally accidental "activation" of other models happens to me but it's stored in undo history so a simple Z stroke to undo keeps my work flow going mostly uninterrupted. If none of the things already suggested help your problem, it might be something you'll just end up having to work around. *shrug* I personally use…