So I gave myself a debug stick and tried it out on some blocks, and then got a sign from the creative inventory and then placed the sign, then I got out the debug stick and left-clicked the sign, and nothing seems to be working! Please fix this in 1.16.3!
Thank you for your report!
However, this issue won't be fixed.
Any issues regarding block states being created or changed by using the Debug Stick are not accepted on the bug tracker according to this reddit post from Mojang.