Messages not decrypted / synced when logging into new Element Desktop installation

### Steps to reproduce

1. I have quite a few sessions, some Element Android, some Nheko, etc.
2. If i login into a new client, for example Nheko on a newly installed OS it works well after verifying, all (most) of the old chats are readable.
3. If i login into a new Element Desktop client this does not work, i cannot see my old messages

For clarity: I am not talking about messages in rooms before i joined them, i really mean the messages i can read on all other sessions...

### Outcome

#### What did you expect?
Element should work

#### What happened instead?
Element shows "Unable to decrypt message" for all messages

### Operating system

Windows

### Application version

1.12.4

### How did you install the app?

winget or choco idk.

### Homeserver

Synapse 1.143.0

### Will you send logs?

Yes