O
One Day
Back home now and had a closer look. I didn't pick up on the uncommisioned ufh part.
I'd say that it's primarily the additional moisture of the extended set not yet gone, and in part - moisture rising from the screed still.
Good sign is the dryness around the grout joints. I think this will dry out but could take quite some time yet...
For future - please use Ditra and a rapidset. That would mean you could fix safely onto uncommissioned heated screed and no risk of residual moisture lurking in the adhesive.
I'd say that it's primarily the additional moisture of the extended set not yet gone, and in part - moisture rising from the screed still.
Good sign is the dryness around the grout joints. I think this will dry out but could take quite some time yet...
For future - please use Ditra and a rapidset. That would mean you could fix safely onto uncommissioned heated screed and no risk of residual moisture lurking in the adhesive.