It was in 6.2, save continued from about v3, but I reprogrammed the planters in version 5 I think? Here's the script, he was just endlessly cycling through the three steps of find-move-plant
Hmmm, I just erased him and gave him the exact same steps and he now plants them properly. All other planters on the save still glitching.
So looks like the bug just held on from the older version?