OutputSignal tag doesn't work

Please provide more information - which command did you use?
My guess is that the comparator immediately updated as soon as you ran the command and changed back the value of OutputSignal to the correct value.

If you mean the command

/setblock ~ ~ ~ powered_comparator 1 replace {OutputSignal:4}

/setblock ~ ~ ~ powered_comparator 1 replace {OutputSignal:4}

But could be a general block update issue that for example the comparator recieves and update but recognizes that it has no power source

@[Mod] Synchuck

No, if you set the OutputSignal to some value, then update the comparator, them check the blockdata, the OutputSignal will still be what you set it to. The comparator seems to just completly ignore the tag.

Ticket resolved as incomplete, because no answer in a reasonable amount of time (1+ year), if it still happens, please update the ticket.