We've found a way how to fix problem with "?" sign instead of degree sign.
Actually the reason is that ICAD 6.6 used in Carlson2011/2012 had additional way to represent degree sign, but it is not
supported by Carlson 2013/2014 or AutoCAD.
So, there is a workaround:
1) If you notice that degree symbols look like a question signs in your drawing - double click on Text/MText entity to
see its properties (or open Text/Mtext editor, or print the text content to the command line by LIST command).
2) In the Property windows look for Contents field, copy that rectangle sign which is shown instead of degree sign
(select the symbol -> Right mouse click -> Copy).
3) From the command line - call FIND command
4) Paste copied rectangle to "Find what" field
5) Mark "Single-line or multiline text" checkbox
6) Set the focus to "Replace with" field, press and hold ALT button, type: 0176 - degree sign should appear in this
field
7) Click "Replace All"