You mean the prefix symbol shows up as square? That's probably because the text style doesn't have that character. I.e. use a text font sporting that character.
the same front is used for text and spot elevation
I would use different font from Arial to Arial Unicode MS
Re: Is it possible to add a symbol to a spot elevation?
What kind of symbol? Like a plus-minus symbol or a musical note symbol? 😉
Paste one from your Window's Character Map into the prefix or suffix field under the instance properties of the Spot Anno.
Open and Use Character Map in Windows | Tutorials (tenforums.com)
is was the
@syman2000 Than you, approached it