"Share encrypted history" not working

### Steps to reproduce

Hello,
I've read this article about Share encrypted history https://element.io/blog/seamless-encrypted-history-sharing-arrives-in-element/ and I wonder how to make it working.
We are using synapse 1.157.2 and Element 1.12.24.
We have encrypted room with "Members (full history)" activated and still, when I invite someone, this user doesn't show history but only "You don't have access to this message".
What should we do to make it working?

Both user, the one inviting and the one invited have only one device and are all verified and users have verify each other.

### Outcome

#### What did you expect?
After inviting the user, this user should get access to history of the room

#### What happened instead?
All message are replaced with "You don't have access to this message".

### Operating system

Zorin 18

### Browser information

Firefox 152

### URL for webapp

_No response_

### Application version

1.12.24

### Homeserver

1.157.2

### Will you send logs?

Yes

No files, tests, or entry points are named. Start by reproducing the issue with Synapse 1.157.2 and Element 1.12.24 using the stated encrypted-room and device-verification setup; done means an invited user can read the room's prior messages instead of seeing access errors.

Written by the indexing model from the issue text.