In MSP, it is possible to have milestones that have multiple days duration, but it is against Clarity definition of a milestone (it should also not have assignments nor actuals). Saving a project with milestones that do not fulfill these conditions is possible from MSP to Clarity.
Steps to Reproduce:
Expected results: Save fails. Milestones in Clarity are expected to start and finish the same day (no duration).
Actual results: Project is saved successfully. Clarity now have 3 milestones with 1 month duration, 2 milestones with assignments and 1 milestone with assignments and actuals.
There are some features from MSP that Customers expect to work even when they are integrated with Clarity.
The current design allows Milestones that come from MSP to have durations longer than zero (i.e.: start and finish dates are not the same), assignments, and/or actuals.
Release : All
Component : CLARITY MICROSOFT PROJECT (MSP)
Clarity will not allow toggling the Milestone checkbox (it will be grayed out, read-only) once it contains assignments or actuals. This can be switched again opening the project in MSP and saving the project back.
In order to restrict this functionality via the Clarity - Microsoft Project integration (for example, with a toggle to enable/disable this behavior), it would be necessary to work on this as an Enhancement.