There appears to have been a change to the logic in the planet management screen for adding new tiles for development. The screen snapshot below shows what a section of the planet management screen looks like when my cursor is somewhere else. Note that there are "+" signs indicating that those to regions can be selected to turn into tiles available for development. So far, so good.
Here is the problem: When I move my cursor to another region that is not yet a cell that can be developed, a "+" appears in that region as shown in the second screen snapshot below (my screen capture software does not show the cursor, but it is where the new "+" sign is). When I click on the "+" sign it gets a bright border as shown in the third screen snapshot below, but nothing else happens. The popup that would normally allow me to choose the method to use to develop the region (i.e. Soil Enhancement, Resequencing Station, etc.) does not appear.
Recommendation: If you want the new "+" sign to work like the others, enable the popup. If you do not want users to be able to develop these regions, do not make the "+" sign appear.