When using Lua Combinator 3 mod for alerts with speakers in current Factorio 0.18, noticed issue doing the following:

• Place Lua Combinator with output['signal-U'] = 1 code.
• Place (powered) Programmable Speaker with signal-U > 0 triggering condition.
• Connect the two with Red Wire.

Expected result: Programmable Speaker emits whatever sound was set there, its activity led lights up.
Actual result: no sound, leds are inactive.

Using same speaker with other combinators seem to work as expected though.
I.e. them emitting same signal triggers the sound and led indication on the speaker entity.

Looking at which mods affected Programmable Speaker, found this one, disabled it, repeated exact same sequence of actions above from same save, and speaker worked fine, which leads me to believe that there might be some weird interaction between Lua Combinator 3 mod and this one.
There was a dozen other mods active aside from above two atm, so not entirely sure if issue is reproducible with just the above setup.

Didn't look into it any more than that unfortunately, but seeing that there seem to be a report about kinda-similar combinator issue here, thought to report this one as well, in case you might be familiar with what might cause such third-party combinator issues already.

There was a dozen other mods active aside from above two atm, so not entirely sure if issue is reproducible with just the above setup.

Confirmed that issue is reproducible with just Factorio 0.18.47 + LuaCombinator3_0.18.9.zip + attach-notes_0.4.3.zip on a new game.
Not sure if it can be fixed on Lua Combinator 3 side, as that mod doesn't seem to be maintained atm.

This is a bug in Lua Combinator 3, I cant fix it

Fair enough, oh well.