Help making Photos slideshow the same order as album

I am trying to make a slideshow via Photos on this iMac. Have latest OS (10.13.1) and Photos (3.0). In the past, when I used the “create slideshow” command for a project, selecting all the photos in a specific album, the slideshow would show the slides in the order they appeared in the album. It is no longer doing this; they appear random, but always in the same random order when the slideshow is replayed. When I use the quick commands to do a slideshow (not making a full-fledged project, in other words), the slideshow shows them in the same order as in the album. I am aware of previous discussions involving the different orders caused by upload vice date taken, but that does not seem to be the case here. I just photographed my iMac screen with my iPhone, with 5 screens, each showing a single number from 1 to 5. When I downloaded these photos to Photos (sigh), the same problem happens: they appear 1-2-3-4-5 in the quick slideshow modes, but were repeatedly randomly distributed…in the same order…when trying to build a project. I need to go the project route because I need multiple songs for this slideshow, and because moving the photos individually, once the slideshow is created, is a nightmare with 100+ photos. I also have rebuilt the photo library. Any help/guidance/tips to make a slideshow project appear in the same order as the album from which it is made would be appreciated!