One image into multiple files?

Hello community,

I have an image in Photoshop that I want to divide into multiple Different images that will save as Separate files. To be more exact, in this case I have an image that is 800 px wide by 3720px tall. I want to divide it horizontally into separate 800 by 1280px images that will save as their own individual files. I used to do this by using the slice tool and creating the segments that I wanted, and saving it with the save-to-web (legacy) option. This got me the separate files I wanted. However after an update a few days ago, that save option is grayed out in the menus for me. I understand the save-for-web is being phased out in favor or Export-as, but this new option will not recognize the slices and so it saves my image as one file. Is there a way to get save-for-web back, or is there a new way to do something like this? (Eventually I want my files to be jpg).

I read that certain settings were needed to make save-for-web work, but I believe I have those settings correct; my image mode is 8-bit and in grey scale. I have un-installed and re installed photoshop as well.

thank you