[mc 1.12.2 w/ sevtech pack] Rock crystal tool block breaking bugged in server only

[BLovegrove]

An old version so not expecting a response, but haven't noticed this anywhere in the reports so figured it was worth a shot given how popular SevTech and similar 1.12 packs with this mod still are.

When in multiplayer, if I break anything other than vanilla solid blocks meant for the respective tool (wood planks are fine, but not stairs for example) then the block breaks quickly as expected, but pops back for a solid 5+ seconds as if I was having massive TPS lag despite the rest of the game continuing fine in the background. There are no log outputs during this time on either the server or client. I'm completely at a loss because this doesn't happen in single player.

Any help would be appreciated (: I can provide log files etc if you think that'll help, but I'm praying this is something that a slight update or something will fix so I don't have to either forgo the tools or break the pack.

The version of astral I'm running is 1.12.2-1.1-.21 in SevTech V3.2.3 (the latest one)