I'm experiencing an issue with workflow rules and the auto-updating of fields based on triggers.I have successfully implemented these rules in the past, but now with particular types of fields it does not seem to work.

What I'm trying to accomplish specifically is this:

1. A new record is created via web form 

2. When a particular Single Line field contains specific text strings (of several different kinds), a checkbox gets ticked

I have programmed all the different types of text strings as OR conditions (a is b OR a is c OR a is d etc.).

When a record is created with any of those strings, however, the rule doesn't get triggered. Is it because these rules don't really work with Single Line fields?