At least not until either a large period of time has elapsed or I manually place another block near them do they seem to pick up.

Is this on a server? SP Game?

If SP Game what are the specs of the machine running it.

Are you holding right click or just right clicking each one?

Also that looks like it's an older version of blockcraftery, I don't think the update fixes it but do you mind trying?

Apologies, I didn't realise the in-game version number didn't match up. This is blockcraftery-1.12.2-1.1.0.jar.

This is a server, however it's a test server set up running on my machine which was ALSO running the client as well, so I imagine that could be a bit of an issue. However, I wasn't suffering any other issues that could be related to slowness or slow TPS.

I was right clicking individually on each one, and the texture was immediately updated as soon as I placed a block which triggered some sort of chunk update. In fact, I honestly believe it was linked to chunk updates because doing a line, then placing a block, (although I didn't count it), only seemed to affect the blocks in that chunk.