ApplicativeAlgorithmsPage does not work in Designer

[omarji]

After getting PropertyPages DLL reference from an older sample (10.2.1) and compiling, the algorithm and its page are displayed correctly in ArcMap and working as expected.

But when going into Designer to configure whether the algorithm is Visible/Editable the editable checkbox does not check (always unchecked) and the property page button is always disabled.

I tried to make multiple changes but to no avail. None worked. Is there a way to fix this? (I am on 10.6.1)