Two tabs in a Private window don't display in the tab bar

When I wasn’t able to see a tab I wanted to return to displayed in any open window, I checked in my tab manager (Tabli) and that tab and one other that didn’t display in the tab bar were both shown.

When I clicked (in Tabli) on the one I wanted get back to, it opened – but still was not displayed in the tab bar.

Not something that’s ever happened before.

Both tabs were in a Private window.

After some further navigation outside of that window, when I returned to that window they finally were back.

Anyone have any ideas as to what causes the tab display in the tab bar to temporarily not work for certain tabs?

Thanks.

Brave browser v. 1.21.73
OS Mojave 10.14.3