errors in calculated concatenated unique ids

[LynnBerni]

We are generating unique sample id's based on the following calculation: 

concat('MA ',once(format-date(now(), '%Y%m%d %H%M%S%3')))

It seemed to have been working just fine, until I noticed a couple of funky ids, where the concatenated "MA" is being added multiple times!  (see screenshot).  Any idea what's going on here? 

[JamesTedrick]

Hi Lynn,

It certainly appears that the concatenation occurred multiple times, though I would also expect the data portion to have been repeated as well.  I noticed that these were collected on August 10th; a bit after that, a hotfix was released that changed the behavior of calculations when opening surveys from the Inbox (see https://community.esri.com/groups/survey123/blog/2018/08/16/minor-update-to-survey123-available-augu... ) - does this occur with any later surveys?