Snapcraft promote refuses to act when arch is relased in an unrelated channel

Curiously, since the release of Firefox and Thunderbird Risc builds to beta, Snapcraft’s promote command is refusing to act on candidate->stable:

The ‘candidate’ channel for ‘thunderbird’ does not form a complete set.
There is no revision released for the following architectures: “‘riscv64’”. Ensure the selected channel contains released revisions for all architectures.

Neither stable nor candidate have had any Risc release yet, so I misinterpreted that as simply a warning for Risc but that the promotion was done for other architectures.

So now I have to go to https://snapcraft.io/thunderbird/releases to do the release, which is a tad less eficient.

Is this a bug in Snapcraft promote?

This was brought to my attention by Thunderbird esr stable and lastest stable branch.