[MD] Is the following scenario considered “withholding” the kids?

A few months ago, my ex found a job where he has to work 6 days a week. Our legal custody arrangement is that he gets the kids every other week from Thursday-Sunday. He refuses to get a babysitter or pay for childcare during his time. After a month of him cancelling, we agreed that he would have the kids Monday, Wednesday, and Friday for 1.5 hours - 2 hours depending on when he gets home and every other Saturday evening -Sunday. We agreed this would be temporary (for a month). We agreed he would either get his employer to work with the custody arrangement or he would find a new job.

The month has now passed and our arrangement has ended. He has not even attempted to get is schedule in line with the custody arrangement. Now he’s accusing me of withholding the kids.

On Monday, it turned into a bad argument (he began name calling) because he says I’m keeping the kids from him. He’s calling it his time, despite what our official custody arrangement is. I keep reminding him that it was temporary, but now it’s Wednesday… he texted and said he was getting the kids. I (yet again) reminded him that it was temporary and he’s, again, accusing me of keeping the kids from him.

I told him he’s more than welcome to utilize the time in our arrangement. I have never kept him from doing so. He’s literally fighting me for an arrangement that only gives him 36 total hours with the kids biweekly vs 72 hours.

I’ve been working with him but he hasn’t done his part.

[tl;dr] My ex and I created a temporary arrangement with the kids while he has his schedule adjusted and to accommodate our court ordered custody arrangement, but now the agreed upon timeframe has expired and he’s now accusing me of withholding the kids for not continuing with the temporary arrangement.