@carloferrigno here is the post with instructions to fix the problem with building images, as already mentioned by @tolevski
For the warning banner, we are fixing it on our side. In short, pinning memory requirements triggers that warning even if sessions with enough memory are available. You can safely ignore it for now. The fix should be rolled out within a few days.
Sorry for the inconvenience; sadly, a few things piled up with this release since it brings quite a few changes in many parts of the system.