Problem with the Pause button in Lumin App

[emilien]

Hello,
I'm using minimserver installed on my Nas Synology DS414, with an amplifier/network player CLASSE Sigma 2200i, and use Lumin App as a control point (with Buble Upnp server installed on the NAS to have the Sigma as an Open Home renderer).
I can't use the "Pause" button during playback : anything is going on when I'm pressing this button.
Do you have an idea about this issue?
N.B. I just changed my media renderer, I was using a Marantz MCR 611 before (when the same NAS/Minimserver/Lumin app settings) and I didn't have this issue.

Thank you so much for your help,
Best,
Emilien