Inaccurate guest count shown on some workspace

Issue Summary

After removing a guest from a workspace the collaborator count still shows the original number. It's not reduced after removing the guests. 

sample affected Trello memberID: 5e9665b3a9a8b0683d6be611
Sample affected WS ID: 640262d570731f5857cd0037

Steps to Reproduce

1. unable to replicate issue outside of affected user environments 

Expected Results

collaborator count matches number of collaborators shown int he UI

Actual Results

collaborator count is higher than the number of guests shown in the UI 

Workaround

create a board or add a workspace member, them downgrade them to a guest. These actions should correct the collaboration count.