I don't know if this is a bug but there are some machine blocks that simply do not have any recipe or that JEI can show at all.
Affected blocks are:

• Burning Chamber - Uncraftable / No recipe (cannot make crucible multiblock)
• Electrolyser - Uncraftable / No recipe

Using 'R' to get the recipe does nothing when JEI is installed. Is this a broken recipe or WIP block at this time?

Mods:
Immersive Industry: v5.0.7
Immersive Engineering: v1.1 Beta
JustEnoughItems: v7.7.1.150
Forge: 36.2.21 (Minecraft 1.16.5)

Nevermind, I have just re-read the page and saw this mentioned. Closing this issue.