It happens to me regularly that, after compiling a package, all blank lines disappear. The result looks like this:



The blank lines are still there, because they still have their line number. But their display is collapsed to 1 pixel high, or something like that.

Unfortunately I can't consistently reproduce this. But here's everything I know:
* This happens regardless of whether I use F8 or the toolbar icon.
* This only happens after a successful compilation, and never when there are compilation errors.
* After it happens, pressing Control-Z to undo the last edit fixes the display.
* After it happens, immediately compiling again (sometimes 2 or 3 times) fixes the display.
* It may be necessary to have a number of other windows open and the Window List displayed for it to happen.

I'd love to see this fixed, but I don't know what I can do to help you fix it. Please let me know if you have any ideas.

Version 15.0.4.2064 on Windows 10.

Could it be the Beautifier issue?
Try to uncheck every ckeckbox in Prefs\User interface\PLSQL beautifier, remove rules file, restart program and try experiment again.

Thanks, good idea.

The beautifier doesn't seem to be involved. The problem appears just as sporadically with all beautifier setting checkboxes unchecked.