Recurring payments regression?

1.0 Problem/Motivation

I've had a form on a Drupal 7 site for a year or two which exposes the "Frequency of Installments" contribution field as a User Select, with "- No installments -" and "year" as options in the webform display. That is set up as a static select and the labels on those are "Do not renew automatically" and "Renew automatically each year". I have "Number of Installments" set up as a hidden field that is set to 0, to make it an open ended recurring payment. Just recently I've received reports that the payment form is no longer working.

When I try to test the form without selecting "Renew automatically" I see this error at the top:

"recurFrequencyUnit must be day|week|month|year"

I tried removing the "- No installments -" option but the same error occurs if I don't check the option to renew yearly.

If I do check the annual renewal option, I'm seeing this error now:

recurInstallments must be 0 or a positive integer

Has anything changed related to recurring payments in this module (or CiviCRM core) recently?