Display lone pairs on carbon atoms

I am using Marvin JS as a web-based application for the students in my organic chemistry courses. It does just about everything that I need in an editor, and since it is a javascript application, it works on most if not all mobile devices. However, it will not display lone pairs on carbon atoms, even when those carbons are marked as anions and "Show Lone Pairs" is checked.

Without the ability to show lone pairs on carbanions, the mechanisms of many reactions cannot be properly represented even with the electron flow arrow tools. Without the lone pair on the carbon atom, you cannot click on that carbon atom using the electron flow double arrow. 

I am using Marvin JS 15.2.23.

Dear bnnorris,

I apologize for the late answer. I was not able to reproduce this problem in our site (as you can see in the attached picture). Could you try it please on our side? And could you send us the problematic structure? Can you see  lone pair on another atoms like oxigen?

I am looking forward to your reply.

Best regards,

Efi

Efi,

Thanks for your response.

I have confirmed that I can view lone pairs on carbon atoms (and thus draw arrows) at https://marvinjs-demo.chemaxon.com/latest/demo.html, which is v 15.6.15 and our install at http://louis.frostburg.edu/MarvinJS/, which is 15.2.23.

The problem appears to be how MarvinJS is interacting with the Moodle plugin (written in php and python) that is calling it. The plugin was written for an older version of MarvinJS. I will see if I can troubleshoot the code in the plugin, and if not, I'll post the parts of the code that call MarvinJS. 

Thank you for the information. Please let us know whether they could upgrade the Moodle plugin.

Best regards,

Efi