I'm experienced with PSE but just upgraded from PSE 9 to PSE 2020 and am struggling with different procedures, specifically Photomerge.
I've found the Photomerge in the "Guided" area of PSE and managed to select a couple of images to merge. Despite the fact that I can visually see overlap in the two images, PSE refuses to merge the two. If I ran into a similar problem with PSE 9, I could choose to manually align the images rather than let the program do automerge. I poked around and found what appears to be the modern version of the manual merge (called Reposition) but that still does not work. The images don't merge and I don't get a screen where I can manually move the images to merge them. There must be some commands I'm overlooking but I sure can't find them. Any help would be appreciated.
An old school manual merge technique begins with creating a single document that contains both images, ie: each image will be on it's own layer inside the same document. To accomplish this, "place" or "copy/paste" image B on top of image A. You'll need to resize the width of your canvas to approx twice the horiontal dimension of the larger image to allow room for both. This will be too much canvas for your exact needs right now, but later on, you can easily crop away uneeded canvas area. I hope you're with me so far.
Now, select the top layer and change it's opacity to around 50% so you can see the bottom layer through it. You can see both layers now and dragging the top one (or use arrow keys) to align with the underlying layer should be relatively easy.
Afterward, return the opacity slider to 100% and see what you think. If things aren't perfect, remember you still have rotate, transform, move, zoom, straighten (etc) tools available to best align the two layers. Once you're happy with your work, Merge the two layers, then crop your completed document to remove unwanted canvas space.
I'll need to hand your Guided > Photomerge mystery off to someone else to assist with unless pressing ctl-k (cmd-k on Mac) and then clicking the button Reset preferences on next launch fixes it. Hope you find this helpful.
Thanks for the suggested workaround. I definitely follow your logic and think it would work. However, I have a LOT of images to merge and am afraid the workaround would take significantly more time than using a workable PhotoMerge function. Not sure about your final suggestion with the ctl-k and Reset Preferences on Next Launch. What would I hope to accomplish and exactly when would I try this? While PSE is open and running? When I shut down PSE? When I start up PSE?
A big thanks for the workaround, though.
I just received from someone at Adobe a link to a YouTube video covering the PhotoMerge. The main point: Supposedly the PhotoMerge only works with images arranged horizontally such as you'd take when a subject is too wide. It apparently does not work with vertical images such as you'd take when a subject is too tall. Interesting. I have been able to get limited success by rotating my images 90 degrees and then trying the merge. However, some still do not merge and I still haven't gotten a response on the manual repositioning feature available in PSE 9.
A second comment about your method of merging images: It does work and it's not as cumbersome as I first thought. Not quite as fast as the manual merge I could get with the old PSE but much faster than turning my images 90 degrees and fiddling around with the PhotoMerge (which still doesn't merge some images). I don't need to change opacity; I just paste one image above the other and slide the pasted image around until it matches. Thanks again for the suggestion.
The shortcut control-k > Reset preferences on next launch button is just quicker than the Edit > Preferences > General method of getting to the same screen. Either way works. Clicking the button resets your preferences next time you launch Photoshop Elements -- so invoke the shortcut while PSE is running. Resetting preferences can sometimes fix issues like the one you're having. It may not work but no harm in trying.