API integration

Description	Ticket	Severity
In Milestone Publish messages, system dates (e.g., updated_at) were not in the expected YYYY-MM-DDTHH:MM:SS.MSS-UTCoffset datetime format. We corrected this issue and Milestone Publish messages now use ISO datetime format. Note that this correction also updated Activity Change messages to ISO datetime format.	CHK-46501	2
Intermittently, response time for Artifacts GET messages was longer than expected and could result in timeout errors.	CHK-46530	3
After creating a site via the Study sites POST API, the items created for the new site did not accept attachments as expected.	CHK-46574	1