Thanks for posting about this, the 00000 required a code fix, and the regex does not work too and required some changes, you need to do the following:
drag a JS view to your page, and add this code:
masksetting = {mask: /^[a-zA-Z0-9_]*$/}
Then in your Mask settings you will need to add the mask variable name:

that should make it work, and you will be able to use all the mask options on the help page, for this to work you need v8.0.29
Max, ChronoForms developer
ChronoMyAdmin: Database administration within Joomla, no phpMyAdmin needed.
ChronoMails simplifies Joomla email: newsletters, logging, and custom templates.
1- yes
2- Unfortunately it's not available or Github, please give me few hours to prepare the installer, I will post here when it's ready
Max, ChronoForms developer
ChronoMyAdmin: Database administration within Joomla, no phpMyAdmin needed.
ChronoMails simplifies Joomla email: newsletters, logging, and custom templates.
Max, ChronoForms developer
ChronoMyAdmin: Database administration within Joomla, no phpMyAdmin needed.
ChronoMails simplifies Joomla email: newsletters, logging, and custom templates.
Please download the new v8.0.30 (download again now as I have applied a patch for this), and test this issue, I think it should be fixed
And do not put any login details here, this is a public forum and hackers can use the details to break your website, I did not login!
Max, ChronoForms developer
ChronoMyAdmin: Database administration within Joomla, no phpMyAdmin needed.
ChronoMails simplifies Joomla email: newsletters, logging, and custom templates.