How to Create an unrestricted Plan that allows employees to enroll any time of the year?

We are offering a new plan with a few different options that is NOT in program. We want to allow our employees to have the option to opt in or out of coverage at any point in the year. I was able to get the new hire situation work by running the 'Evaluate Unrestricted Event Participation' scheduled process after I hired the employee. Their enrollment window was 30 days as specified in the new plan that I created.

However, for CURRENT employees, I am unable to find a way to allow enrollment. I also went down the route of trying to create a self-reportable unrestricted life event, but don't see that option. I also tried creating an open scheduled unrestricted on the plan with an end date of 12/31/4712 but that isn't working either.