When I added ignitehud mod, the thermometer GUI disappeared

I see that you have the X and Y GUI coordinates set. If you want to use absolute XY positioning, you have to turn off the "Stack X" option (the stack option causes the bar to be integrated into the vanilla UI).

But if you already have turned off the stacking, then it's probably that ignitehud is messing with the rendering system, and in that case there is really not much I can do.

Closing due to inactivity.