I have the Premium version and for some reason I cannot set a seat alert in LO flights for any seat that is unassigned prior to OLCI.

On LO seat maps, any seat in Y that has not already been blocked or selected (e.g. by someone with a fare that includes seat selection) will show up as 'Paid and Premium' (according to the symbols). These are unassigned seats that can be reserved prior to OLCI for a fixed fee (10EUR/40PN), which generally covers the bulk of seats in Y on LO flights (most people travel on discounted fares and get assigned seats at check-in).

However, I find that for all these seats there is no way of adding them to any seat alert. If you select the check box 'Include Paid seats' it does not allow you to tick any of the seat options below (e.g. Aisle, Window, Exit Row), so you cannot create a Seat Alert when this box is ticked.
But if you untick it then try to create any seat alert then all of these seats are unselectable (only Blocked/Occupied show).

I know this used to work as I have a saved notification from last year for WAW-POZ where I had selected 'Include Paid seats' and had specific seats defined in the seat alert.
For some reason there now doesn't seem to be any way to get it work with Paid seats (Premium and Blocked don't cause any issues).

I tried doing this with the Seat Alerts mobile app also and the results are the same (no seats of any kind are selectable when Paid seats are included).