As said in the title, the Linked Transmitter can't be placed on non-vanilla buttons.

I'm playing on Minecraft 1.20.1, Forge Loader.

Screenshot:

Multiple technical difficulties make it almost impossible for C:Connected to generate linked variants of modded buttons on the fly.

• All mods register their blocks in parallel, so there is no guarantee that C:Connected can discover all modded buttons in time for registration.
• Linked buttons require custom block states which can be generated on the fly, but it is not always possible for C:Connected to find the correct path to the model files of modded buttons (especially if mods use a custom naming scheme for their buttons)
• When mods like Jade are installed, linked buttons also require translations, which are also difficult to generate.
• Some modded buttons may have custom logic that the linked variants cannot replicate.

Adding new blocks programmatically is difficult in general, so I only plan to support vanilla buttons and a select few mods if there is popular demand.

That's a shame. I do hope this can be done in the future perhaps.
Also, keep up the good work on the mod, I'm enjoying it so far.