For some reason or another, the automated system which checks polarity and detects which clamps are on which leg etc… can’t figure things out. So Sense support may have to intervene.
You can open a support ticket for the new monitor if you want, but the automated process has already flagged it for help, so the extra ticket should not be necessary. It is possible it will also sort itself out over the weekend. I suggest that other than making sure that the CT clamps are fully closed, don’t move anything.
I often see on the forums where people are told that signal check failing is because they installed the CT clamps facing the wrong way and they should fix it. While yes, Sense gives instructions on which way to make them face, in the end it doesn’t matter as they can correct for it in software. But when people start moving the clamps while the signal check process is going on, then the system gets even more confused.
It does mean you are probably waiting until Monday for a resolution when support opens up.