I think this bug occurs if you place a wire line, break a block in the middle, then replace the wire. The signal doesn't connect up properly. I'll do some testing in the meantime.

EDIT: Steps to reproduce

1. Have power enter a block from 1 edge
2. Place a wire interior to the adjacent block, that is not powered by the signal
3. Place a wire connected to the signal
4. The signal no longer passes through the wire as expected

For the infinite signal:

1. Have power enter a block from 1 edge
2. Place a wire connecting to that signal
3. Place a wire interior to the previous wire that is not connected to the wire
4. Remove the power input. The wire will remain powered

Hey man, ty for the report. The complicated fixes that had to be made with the new update order has apparently introduced a regression that slipped the checks ;; That's gonna be a "Vanilla Redstone one" - aka a horrible one to fix ;). I presume the neighbour updates of the track networks interfere now.

... It is likely that late 1.20.x (neo:forge + fabric) may be affected as well, this was a vanilla change.

Yeah. Easy to work around for now, just less compact wiring

For 1.21 fabric I just pushed a beta for testing. It was a regression issue when working around changed redstone handling in vanilla and mods. Could you risk a glimpse at that? I was not able to test it in depth (like what happens to Dropper triggering from various sides, or e.g. Alternate Current and similar mods go along with it) - so "maybe fxed" ;).

Download link is: https://modrinth.com/mod/redstonepen/version/1.11.36

Oky the actual fix is out. There is still the visual glitch when placing, I could not track that - the debug info show that the block knows the correct values, so this looks as having something to do with the network synchronization - which is very strange.

For the next while we'll have to live with it, I have to defer the task for timing reasons.

Fixes are up on the distribution platforms. The visual glitch is considered in a separate thread/issue.