ACR, panoramas and perspective

You need to pay attention to the stacking order, which you can do in Photoshop, but I'm not sure that's possible in ACR. I haven't really looked. I do this in Photoshop because you have much more control there. Use Auto-align > Auto-blend, not Photomerge.

In Photoshop, the frame at the bottom of the stack is the reference frame that the others align to. So you put the center frame there. Then you get the "butterfly" shape you want.

That said, prepare your files well in ACR. Correct perspective and vignetting, and do as much global correction as possible. Make sure overall exposure is the same.

generally the adobe stitching engine is kind of a random hit and miss thing when it comes to proper results. some colleagues in the 360° business say PS has the worst stitcher and the best blender 🙂 
if you've material not being correctly captured or being challenging otherwise, you need a more robust solution like the mentioned MS ICE.

if you really want to tackle with everything and want professional results, try https://ptgui.com. it's the industry standard for a reason.

@stephan_7311 Nope! You're not overlooking something major; it's a difference in design philosophy and capabilities. Microsoft ICE, despite its age, was a highly specialized and effective tool for panorama stitching, particularly for its flexibility in handling various shooting conditions and projections. Adobe's tools are integrated into a broader ecosystem and excel at other aspects, but sometimes fall short on niche, yet critical, features like robust perspective panorama stitching. Stick with Microsoft ICE (if you still have it or can find a safe download, as Microsoft no longer officially offers it)