I've got exactly the same problem as the OP on FreeCAD 0.19:
Was using FreeCAD 0.18.x on Ubuntu 18.04 before, and had the ability to select the center of a circle for dimensioning...got a nice TechDraw thing all up and ready to go. After upgrading Ubuntu and FreeCAD, I realized I'd made a little mistake, and wanted to create a different dimension. But there's nothing to select for the centers of the holes!
Preferences -> TechDraw -> Annotation -> Show Center Marks is checked.
Tried creating a new TechDraw View--but the center marks do not show on it either.
How in the world do I get a dimension set to the center of a drilled hole now??!
OS: Ubuntu 22.04 LTS (KDE/plasma)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.
Build type: Release
Python version: 3.10.2
Qt version: 5.15.2
Coin version: 4.0.0
OCC version: 7.5.1
Locale: English/United States (en_US)