Whenever you have issues like this, it is almost always something on the wrong sheet.

Sometimes the easiest way is to go through the sheets one by one.

If you issue the command SAUTOHIDEON you put CC3+ into only displaying one sheet at a time mode. You can then go to the next sheet with the SNEXT command or previous one using SPREV command, or to a specified sheet by using the SSET SheetName command.

There is a small bug where the sheet indicator in the status bar says Common Sheet even if that is not the active sheet. Issuing a REDRAW command (or Ctrl +R) updates this to show the proper sheet.

Once you have identified what is wrong, which should be obvious when you work through the sheets like that, you can turn normal sheet display back on and show all sheets with SHOWSHTF *.

Which kind of object is it? Symbol, polygon? Does it happen in all map styles, or just in your current map? (Try starting a new map in a completely different style and test)

There is one specific quirk in CC3+ that makes this happen. The outline when moving is drawn using an XOR against the background. This basically means that the outline color always will be the exact opposite of the background behind it. But, if there are two entities stacked exactly on top of each other, then you get the reverse of the revers, which means it gets drawn the same as the background.

To add on to Sue's answer, If you need several versions at different scales, you can clone a fill style definition by first picking the desired one to clone, then hitting the New button in the dialog, and give the clone a name. Now you have two versions of the same fill, which can be scaled independently. You can then make another drawing tool that uses the new version of the fill to have two drawing tools with the same fill at different scales.

Autosave deliberately save to a separate file to make sure to not accidentally overwrite your actual map file with what is perhaps unwanted changes, for example when testing things.. This is how autosave works in most software. I guess a more correct name would be "recovery save" or something like that, but autosave has just stuck in most software as the common term. It is not a replacement for manual saves, just an extra layer of security, so yes, you should always manually save before exiting. (Personally, I have autosave on, but the dialog off, so it autosaves silently in the background, which is what most other software does by default)

Something has happened that corrupted the current coordinates, so when zooming, it causes CC3+ to multiply numbers with illegal values, which won't work very well unfortunately.

The easy way to fix it is to just do a View -> Zooms -> To all Text, then pick any text entry in your map. That puts you back into proper coordinates, and zooms should now work fine.