Vote will not be counted if a date that has already passed is checked or an entry containing a date that has already passed is changed
Check a date that has already passed or change an entry containing a date that has already passed. The vote will not be counted. This only happens, if ("maximal number of participants" is activated [at least, if it is set to 1]). Workaround: Set the votes for all past dates to "No" -- the vote will be counted. This may be intentional, but it creates difficulties for people who want to agree on a later date when the earlier date has already passed. At least, a better hint than "choice is not compatible with previous choices" would be helpful.