As stated in the Chapter "My Projects" view of the SnooPI User Manual, the stop sign indicates that a project has timed out. This is also known as the state "Observing Timed Out" which is a state assigned to ObservingUnitSets (OUS) that are no longer eligible to be scheduled on the telescope, due to a conflict between the science goal requirements (observing band, resolution, Largest Angular Scale, and/or timing constraints) and the plans for the rest of the observing season. Common reasons for an OUS being set to Observing Timed Out include: no more observing opportunities for an ephemeris object; the remaining 12-m configuration schedule does not include configurations that are suited to meet the angular resolutions scales necessary for the project; the target(s) requires high frequency observations but are only observable during the day, when such observations are not scheduled (since the daytime atmospheric phase fluctuations are too large).
Any unobservable OUSs for projects awarded an A-grade will have the corresponding Scheduling Blocks (SBs) put in the "suspended" state, and will not be scheduled for observations. These will automatically transfer into the following cycle for completion. The state of unobservable OUSs from lower priority projects will be set to “ObservingTimedOut” and the corresponding Scheduling Blocks (SBs) put into the “suspended” state, meaning that no further observations are possible.
Any unobservable OUS that has been started but not finished will be sent for data processing. These data will go through the official Quality Assurance process (c.f. Chapter "Quality Assurance" of Technical Handbook); however, they will likely not meet the PI science goals on sensitivity (and maybe angular resolution): in this case, they will be marked as QA2-semipass and delivered to the PI.