Brush Sizing Problems in Photoshop

Yup, it was the Caps Lock key. Had to confirm that for myself now that I'm actually in PS and can test.

Semi related…

A couple, or few versions back (I'm currently using the most recent 27.2.0, CC 2026 version in Tahoe), when you first launch PS, it sometimes pay no attention at all to anything from the keyboard. You have to click somewhere away from PS, like the desktop, go right back to PS and then it works.

Otherwise, for brush sizes, I always right-click somewhere on the image, which brings up the brush palette.

Can't be sure as I'm not sitting at my Mac, but I think the cursor toggles between a crosshair and shape when the Caps Lock key is pressed.

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

If the tip above does not work, contact Adobe. Photoshop is not an Apple product.