Since this is the first google result, I registered on this forum to post this video which just solved the issue described here on my 2016 expedition ssv:
If you can't hear your washer fluid pump runing as you press the front sprayer button but the rear sprayer works fine. Here is your fix. 2015 to 2018 Exped...
www.youtube.com
Back story: had a mechanic play around the fuse box while trying to find if my starter issue was related to a relay (it wasn't, starter just failed out of nowhere). He apparently swapped 2 relays. Putting back the "ab" one in the first spot fixed the issue right away.
Hope that'll help someone else some day!