OMEMO + Message Carbons not working with Conversations

I am using Gajim (1.1.3) + OMEMO plugin (2.6.28), both installed from flathub, and the latest version of Conversations on my phone. OMEMO is enabled on both sides. When I write messages using conversations, message carbons are correctly encrypted, sent to Gajim, and decrypted. In the opposite direction, Conversations is unable to decrypt message carbons sent by Gajim. The Conversations OMEMO key is marked as trusted in Gajim. Since Conversations appears to be compatible with quite a few other carbon implementations, I suspect that this issue lies with Gajim, not Conversations (although it could be conversations as well)

Please let me know what additional information I should provide to help figure out where the problem is.