Mac message timestamps getting progressively farther ahead of real time

I recently updated my macOS to High Sierra (10.13.6). Ever since, my outgoing message timestamps have gotten progressively farther ahead of real time. It started out only being a few seconds off but got as bad as fifteen minutes, at which point several outgoing messages started showing as not delivered even though they were. Timestamps and message order are shown correctly on my iPhone.

I found a temporary solution, which is to reset my computer's system management controller (SMC). However, this only fixes the problem for at most a day or two before things begin to get noticeably out of sync again. What can I do to permanently fix this problem?