Players are reporting that to craft, occasionally they have to stand next to their workbench because any further away, and it says "You need a workbench". 

BUT .... If the affected players TP's away then TP's back, the option is there to craft anywhere inside their base.

Any ideas?

Can you have one of the players send you a screenshot of the message they're getting. It will help narrow down where the issue could be coming from.

Sure, I have let them know and should have a screenshot for you the next time it occurs. 

Cheers.