Tools such as Clone Stamp and Healing Brush not using the areas I select??

Hi all,

Hoping someone can help me with the following.

When using certain tools which require selecting an area using the alt key (clone stamp, healing brush), the system seems to ignore the area I've chosen/selected and instead uses a different area of the image for where its pulling the information from.

Have tried resetting the tools but that doesn't work. Every now and then it seems to work properly, but 99% of the time photoshop picks its own area!

I'm running version 20.0.06 of the software

Any help gratefully receieved!

Thanks