Can't edit an attribute table?!

[DanielPhillipsTTU]

Hello All, I'm running the most current version of ARC Pro Desktop and am having an issue when I try to add data to newly created fields in a shapefile (located in a geodatabase and otherwise).  My workflow in the past has been simple: Open the attribute table, add a new field if needed, just click the cell and enter text or numerical data, easy.  Now it appears to be locked?  When I click and type, no data.  I've tried setting up new test colums of different types, tried saving the shapefile outside of a geodatabase, ensured that they are not "read only"--All to no avail.  It's driving me crazy and I'm hoping someone has some advice for what seems to be a really basic function that no longer works! Attaching screenshot of the field that currently shows all null values

[ChristianNoack]

Mine does! It says "This layer is being projected on the fly"

I'm guessing it won't edit because it's a different projection than the map?

[Scott_Harris]

That shouldn't prevent edits from being made, even though it's a best practice to edit in the same coordinate system as the data.

[KeithAddison1]

One possible cause is the layer to be edited not having a coordinate system defined.

[XiclalyMagdaleno]

Hi everyone! If double clicking the cell within the attribute table doesn't activate field to edit, try selecting the column and press F2. After a minute or so, the lock on the cells returns so you may need to repeat the process as needed.