'Requirements not met' on an active mod only means you cannot refund that mod because you have a mod active in another column that you're only meeting the bare minimum active mods for. Easy way to see it: Reset your artifact then activate 3 mods in column 1 and 1 mod in column 2. Hover over the 3 mods in column 1 and you'll see they all have the error as you refunding the column 1 mods would bring you below the 3 mod minimum for the column 2 mod. Activate a 4th mod in column 1, none of column 1 mods will be displaying the 'requirements not met' text as you're above the 3 mod minimum to have the column 2 mod active. Deactivate a mod in column 1 - error text comes back. If the above doesn't describe your particular issue, can you link to a clip explicitly showing it?

That simply means to cant refund them. Has nothing to do with them working or not. You’ll need to refund mod(s) in the last/later columns before you can refund mod(s) in earlier columns.