Just messed up again on Safari Technology Review on both the pinned and unpinned tab.
So far the regular Safari pages are working.
I should add that, in this case, a little earlier my computer locked up and nothing worked other than my mouse cursor would move around, but couldn't click anything and TB did nothing. I had to hold the power button to force a shutdown.
But this is not normally part of this page issue so I'll chalk that part up to coincidence. Next question will be does the same thing eventually happen with regular Safari.
Oh, another thing I've noticed during this is that if I open a new tab and paste in the address, it never works. It seems to close the tab, move to the pinned tab, and the address is just WayTools.com rather than what I pasted. If I paste the full address into the existing, unpinned, tab, then it immediately switches to the main WayTools page again. Only way I seem able to get the status page back is to go back to the link in an email.
If this is limited to Safari technology Preview, it doesn't matter, imo. I mean, it isn't the official Safari, but stuff in it may be added to Safari so it may matter eventually.