User blog comment:MisterWoodhouse/The first migrations to the Unified Community Platform/@comment-34207376-20210112230916/@comment-24053170-20210116205711

Unfortunately this problem doesn't seem to end up being solved.

Comments are generally ported over, but message walls have pretty much been wiped clean on some migrated wikias, and the messages AREN'T returning. There gone for good.

The Kou1 Isekai wikia is one of example of this, as the wiki migrated but the message walls didn't make the transfer and they never ended up being restored even after a few months (not weeks, months).