Screen sharing options

I use Zoom client for Linux, version 5.5.4 (7938.0228) on a Ubuntu 20.04 distribution.

Since yesterday the screen sharing doesn't allow me to share a single window anymore: the only options are sharing the whole screen or sharing the whiteboard, and in the advanced options: sharing a part of the screen. I used to share a single window (my presentation) and I found this very comfortable. Any help will be appreciated, I haven't found any similar post on the forum. Thanks in advance.