Using test build 358, forge 14.23.5.2768, JEI 4.11.0.206, and Immersive Engineering 0.12-86.

Enabling the iconCache makes certain blocks render strangely in JEI. The Floodlight is a confirmed example, and I think the extracting conveyors also suffer from this. In particular, the yellow lamp part of the floodlight is invisible in JEI.

Turns out it could have been caused by an I.E. conflict with connected textures mod. Updating I.E. to release .87 should fix the issue, per its changelog. Haven't tested it yet however.