Using the selection filter, you can select pins directly, and then view the pin numbers in the property window.
Using the symbol I sent you, I have pin 2 on the schematic selected, but on the symbol this is pin 1, because the pin numbers have been swapped.
From the error, I am guessing you have multiple pin 3 at the block level, perhaps because once placed on the schematic, pin numbers are not automatically updated if changed on the symbol.
If you continue to have an issue, call support to setup a web session and review the error.