Issues with compare()

[FishModeler]

I am trying to compare multiple binomial models that have various combinations of variables. When I try to compare(modelnames...), I receive the following error message:
Error in attr(object, "cstanfit")$draws : $ operator not defined for this S4 class

Any insight on what may be causing this? This is a new problem and wasn't having this issue about a month ago.
I have tried using the current version of rethinking, compare will work but it will not save my outputs. I have used @timjzee 's version noted in #443 which will save outputs successfully, but I will receive that error when comparing. I have tried mixing and matching rethinking versions and that does not work.
Cmdnstanr version 0.8.1.9

Thanks!

[rmcelreath]

This looks like a missing class method. I will flag it. Thanks very much for the report.