Description: Red Hat Enterprise Linux release 8.1 (Ootpa)
~ $ wxmaxima

(wxmaxima:5684): Gtk-ERROR **: GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+ 3 in the same process is not supported
Trace/breakpoint trap (core dumped)

Any ideas?

Well I was excited to see wxmaxima as a snap. So I tried it and got exactly the same error as you.
Machine is running ubuntu-mate 19.10, So it might be related to the snap itself or the fact it is pointing to nightly versions according to the description.

wxmaxima  17.04.1  peterpall  -      A nightly build of wxMaxima, a gui for Maxima, a full-featured CAS.

Edit: actually 17.04 is not very latest as the normal repo contains 19.07