lists/members/create_all does not always add the user ids specified in the request.
Sometimes 100% of the users passed to the request are added to the list, sometimes only a couple of users are added, sometime no users at all are added.
I am limiting the number of user ids in a single request under 100 as specified in the docs, and am not trying to add more than 1000 users to the list in total, so this behavior is surprising.
The doc states:
Please note that there can be issues with lists that rapidly remove and add memberships. Take care when using these methods such that you are not too rapidly switching between removals and adds on the same list.
But there is no detail on how often lists can updated, or what specifically causes a list to enter the state where the behavior of the API call becomes nondeterministic.
Any help would be appreciated.