After editing using both Lightroom Develop and then switching to Photoshop Elements 12 and then additionally using some Nik Software embedded as an add on in Photoshop Elements, I try to return to Lightroom. I chose File, then Save. A Save As dialogue box appears. If I choose JPEG, then it's saved as a copy and I have no choice. So I don't choose that. Instead, I leave the format as a TIFF, and I am given the option to Save As A Copy, but I don't choose it and leave the box unchecked. A new dislodge box appears saying: DSC 2910-Edit,Tiff already exists. Do you want to replace it. So I choose to replace it. Why, I don't know, I just choose it. That brings up the Tiff Options and FINALLY I get a chance to save the file as a JPEG, which is what I always wanted and additionally, choose the MacIntosh box for the Compression choice. I press OK. Now I'm done and want to return to Lightroom and see my results in the Library. In Photoshop Elements, I press the Yellow dot to return to Lightroom and I'm met with this cryptic dialogue: "The File Appears To Be Unsupported or Damaged". I disregard this message, and go to the Library in Lightroom Library, and presto, there is the edited photo saved next to the original DNG file. So what is going on? i'm getting the result I want but I'm being warned of some kind of malfeasance I am committing. Can anyone unravel this? Thanks in advance for your analytic thoughts and efforts!
You don't go back to LR to save work you have done in PS Elements or the NIK collection. you do that Before you go back to LR. In fact there is no Save or Save As in LR. So I don't know what you are seeing or from what program but it isn't LR.
Once an image is sent to PS Elements Click the Save Icon or hit Ctrl + s (Windows) or Command + s (Mac) to save the file in the format chosen in the LR external editing preference. Once it is saved as a TIF or PSD any and all work done on that files will always be save to that same file extension. Even if you use one of the NIK plug-ins.