Some icons not displaying on human test

I have a site where the test to see if users are human does not display all of the icons. So far I have noticed that the pencil and diamond icons do not display in Chrome. Just a rectangle box is displayed. It displays fine in Mozilla and Edge. The site is a Joomla site, I have Chronoforms 6 and have just updated to latest version. Any suggestions would be appreciated.

Hi macmumma,
​
I use Chrome and see both the pencil and diamond OK when I test. If you use your bowser web developer tools you may get some idea of what is happening here.
​
Bob