Found that Scannables isn't working with Things. As in the pictures, Scannables will typically render an outline around found blocks, but with Things installed it fails to do so.
Only difference between the two screenshots is Things, no other mods changed, installed, or uninstalled.

Running on MC 1.20.1, Fabric 0.14.24.
Modlist is:
Architectury (9.1.12)
Fabric API (0.90.7)
Forge Config API Port (8.0.0)
owo (0.11.2)
Scannable (1.7.12)
Things (0.3.1 + 1.20)

This was fixed as of 0.3.3, thanks for reporting
Cheers