Turn 'snap to grid' off as this forces your cursor to snap to only the grid co-ordinates so unless they also match your mid points or guidelines you will not be able to snap to those.
With 'grid snap' off you will then be able to snap to your mid points and guide lines.
'S' I believe is the standard 'grid snap' keyboard shortcut to turn it on/off.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11