Anchor points return as a solid black mask in material channels

After updating Substance Painter from version 12.0.3 to 12.1.0, all anchor points connected to material channels no longer return the correct anchor mask. Instead, they produce a completely black mask, even though the anchor levels indicate that the values are within the expected range and are not actually black.

This issue did not occur in version 12.0.3 and appears to have been introduced with the update to 12.1.0.

Expected anchor mask:

Returned anchor in material color channel:

Anchor values in material color channel:

Anchor values in mask: