it is not a bug, MisterCap and you have installed some UI mods that changed techtreepreview.json to show eco indicators under the res icons, with a cost: these mods disable the tech tree preview completely.
Install my mod to fix the problem.
Mod name:
[CMD] Eco indicators and Tech Tree Preview
(search for higsby)
You can also install:
[CMD] Dots for Tech Tree Preview (many colors to choose)