Not short, NRC overselects each year so by the time the first actual board hits for the next FY they have 30% or more of the next FY already selected. Since there are drops/pushes on a regular basis for a variety of things they will need to fill those spots, it is easier to fill that spot with a person who doesn't already have an OCS date then to move a person who does.
May 5th isn't short notice, before the fiasco of Nov 2022 if a person didn't put a date available they would often get a date 4-12 weeks out with the average 6-8 weeks, they are slowly getting back to normal.
The career event I was out a few weeks ago I talked to an OR, I think more like enlisted that helps out the OR, but he said he is hearing a lot of misinformation from other OR's about what is going on with ISEL program but no actual info from NRC. Some are following rumors and some are not, he hasn't heard a person submitting an ISEL and being told "no". What will cause there to be no real affect are those following the rumors.