I'm stuck with Rosa tied on a chair.

I found the way to move in the room, but there's nothing to cut
the rope.

According to walkthroughs I found, there should be a glass
sitting on the shelf near the door that would help, but nothing
like that is visible, only non-interactive items.

I can see it in various screenshots of the room, but the glass
isn't present in the version distributed by GOG.

I tried from the start both with the Mac and Win (updated) version
but the room is the same.

Did the latest update change the puzzles ? How to pass that
specific puzzle ?

That's odd. I played Deception last month and made it through this part of the game without a problem.

Just to be sure, are you referring to the glass shard used to cut the ropes? Joey needs to blow on a cup made of glas (or was it a glass vase?). The glass will fall down, shatters and Rosa can use it to get free.

sadly, I have uninstalled and removed all saves from my PC, so I can't look up or make a screenshot for you.

Nothing on the shelf, and no broken glass on the floor or elsewhere...

Mmm, just did a speed run to the section with an updated 2.0.0 installation (Windows version, on Win XP).

...and the glass is right here and visible.

Two tries with the updated version lead to a dead-end, but the older install works for me.

I can finish the game now, but the mystery remains... ^_^;

I have to correct myself : glass visible with 2.0.0 without the updated graphics,
but no glass with 2.0.1 on Windows XP (32bits) or 1.1.0 on Mac OS X 10.9 Mavericks (64bits).

As I wasn't too far from the end, it's okay, but I'll backup the 2.0.0 installer just in case.

I guess I have found what is causing the issue.

It might be caused by running the game with graphics downgraded to 16 bits (check it by running winsetup.exe). Rather play with 32-bits.
Sadly, if the game has been started with 16-bits graphics, savegames are not comptatible with 32-bits settings. You need to restart from the beginning.