Expired member Renewal Issue - Plan Missing

What should I set 'Can be reactivated if expired or cancelled since more than' to?

That just means the user must wait the selected amount of time before they can renew after having expired. In your case it should just be left as "Can be reactivated anytime".

Also, can I apply this setting to a member who lapsed a few weeks ago - i.e. are these setting live for everyone who fits in the parameters or those that trigger them from now?

Yes, these settings should take affect immediately.

Now, a similar issue on a different plan and member.

Expired on the 25th, manually paid renewal today, we go to renew membership and they are still showing in their plan without the ability to renew.

See the attached image.

Setup as per your previous comments.


Here are the subscription parameters:

And now another member (as per the first post in this topic) that expired in January, has renewed, but no option to put them back on their original plan!!!

There is something really strange happening!


Edit
In subscription parameters, I had to move their status from Expired to Registered Unpaid, which gave me the option to upgrade and create a basket...

Edit your plan and be sure "Manual renewal extends expiration date as follows" is set correctly under the Pricing tab. A renewal extending previous expiration is entirely caused by that parameter not allowing free gaps. This typically should be set to "Renewal starts at expiration date or at payment date - whichever happens last (allows free gap)" to allow for free gaps.

It is set to 'Renewal extends expiration date (without gap or overlap)'.

If they renew after the anniversary of their sign up and within 3 months we want them to continue their membership. After the 3 months, create a new subscription.

If they renew after a month, we do not want them to get 12 months from that date.

You are not allowing for a gap. That's why you're having this issue. The "Can be reactivated if expired or cancelled since less than" parameter takes care of your case for blocking renewals past 3 months. The below is my recommendation for your usecase.

Renewable in advance by: 1 month
Grace period before real expiration: 1 week (7 days)
Can be reactivated if expired or cancelled since less than: 3 months
Manual renewal extends expiration date as follows: Renewal starts at expiration date or at payment date - whichever happens last (allows free gap)

Beyond that I don't know what to suggest except continue to adjust those parameters to meet your needs. As is your plan is behaving correctly as configured.