Forge 1614 for 1.7.10 - in game mod options not working

This is driving me crazy.

The in-game mod options abruptly stopped working. They used to work, but now I get "test1 test2 disabled" instead of my list of mods.

I tried setting up a test directory with just a single mod, the Clock Hud. The Clock Hud has a highly useful in-game config that lets you set the scale and xy location of the display. It's the sort of thing you need in-game, since the cycle is tweak values / check appearance / tweak values again until you get it right.

It doesn't work. All I get is "test1 test2 disabled." Searching on this topics gets a lot of hits for 2014 or so when the feature wasn't implemented, but nothing current and nothing relevant.