Okay, you said that the ram was in there for 4 months... you are barely at 2 months from the earliest possible date. Animals do not have babies when we want them.
So what were the dates the ram went i with them AND what was the date when he came out ????? That's the more important one at this point. And by my math, they could lamb anywhere up until the middle of July,,, if the earliest possible date was Somewhere around Mar 25-30... then add 4 months to that for the latest possible date.....and you are looking at mid-late July.
And yes, it is not uncommon for one or more to not settle... We have cattle that do not always settle to the bull when we want them to.,... and have 2 right now that must've gotten bred the day he got taken out.... because they don't look anywhere near close to calving, and they were confirmed pregnant... shorter bred than the rest... but pregnant.
They could've been bred and aborted the fetus ... maybe in the miserable cold and icy snow??? Who knows what the reason could be.
We had a cow confirmed bred twice... to be sure... finally found a dead calf a few weeks later... had to have been hers since everyone else had a calf... RECHECKED her and she was open... IT HAPPENS.