When I copy numbers using either "Edit/Copy" or "Crtl+C" in Google Sheets on PC and then use "Edit/Paste/Special/Paste Values" or (Crtl+shift+V), the numbers are indeed pasted. They appear normal and are in the formula entry box as numbers, but they are not treated as numbers in GRAPHING.
The only way I can see that they are not "normal" is that they are Left aligned instead of Right aligned. By the way, the prior FORMAT of the cell doesn't change this behavior, but formatting the cell with the numbers in it can be used with FORMAT\NUMBER\"0.0" to make them normal.
I am otherwise either using "Format/Number/Automatic" or "Format/Number/"0.0"
This odd "invisible formatting survives copy pasting and EDIT\PASTE SPECIAL\ PASTE TRANSPOSED.