I'm a human savage forester. I've done both savages and foresters before. I'm positive I never had this issue before (though my last forester was a long time ago).

field <100%hp 100%m 99%mv 6304tnl (22.75%)> l
The Open Plains
You are standing in the middle of what appears to be a nearly endless
plain. All around you one foot tall stalks of dry grass sway to the
gentle breeze which blows through here. The plains are very quiet,
and in fact there seems to be no other traces of life here. There are
no distinguishing features here to guide your path, save the sun, moon
and stars. To the south you think you see a road, and the plains
continue in all other directions.


A small falcon flies over the plains in search of prey.

field <100%hp 100%m 100%mv 6304tnl (22.75%)> creep e
There is not enough cover there to creep.

Happens any time I try to creep onto a field.
Bug or just a change?

It's been like that for every ranger I've played going back to the 1900s.

It has not been like that for every ranger I have played going back to 2000?

I never had problems as a muckdweller or bedouin. Is that a handicap just for foresters?

I checked and, essentially, at some point it was changed such that some rangers can do it and some can't. I'll let you figure it out from there.