[Solved] Can't deploy client Zimlet

Hi. I'm running Zimbra OSE 9.0.0 (p20, Zextras build) and Zextras Suite 3.8.1.  Most stuff is working but I have an issue : I can't deploy the client Zimlet. When trying to do so from the CLI, the command hangs for a few minutes, then displays

[zimbra@zmstore ~]$ zxsuite core doDeployClientZimlet

Unable to communicate with server
[zimbra@zmstore ~]$

(Running in a multi-server, single store env, and trying to deploy it on the store). No obvious error in mailbox.log, I can see the zimlet being downloaded

2022-02-22 13:31:26,113 INFO  [ZxLink Handler Thread] [] extensions - Downloading  https://download.zextras.com/installer/zextras_suite/3.0/com_zextras_client.zip 
2022-02-22 13:31:26,190 INFO  [ZxLink Handler Thread] [] extensions - Downloaded /tmp/zxtmp/com_zextras_client.zip

This setup is with a valid, perpetual suite pro licence. How can I fixe this ?

Regards,

Daniel