Hello @paolacatarechiga,
Thank you for bringing this to our attention. I've checked with our product team, and I can confirm that a bug report has already been filed for the issue you're experiencing with opacity masks not working properly when images are embedded. The product team is actively working on addressing this issue, and you can expect improvements in an upcoming release.
In the meantime, if you'd like to stay updated on the progress, I recommend upvoting this related UserVoice post: Opacity Mask Editing Mode is Broken. This way, you'll receive notifications on any updates regarding this specific problem.
We appreciate your understanding and patience as we work to resolve this issue. If you have any more questions or concerns, feel free to reach out!
Best,
Anshul Saini