Should they all have been accepted? Although award rates very considerably among freelancers, I'd say that on the whole, you're more likely to have your proposal declined than you are to have it accepted. So having a proposal declined isn't really a rarity.
Or are you saying that it seemed strange that they were all declined on the same day? I guess that's just a case of coincidence. Were there a lot of them?
I really hate the emails that say "haha you lose." I like to build myself up to that moment and look at the fails at a certain time of day. Now, I get email notification that I'm the loser at random times of the day. It sucks when it's before coffee and lunch too.
What really annoys me is when I get that decline note from Upwork and then they say, "But never mind the right job is out there for you" (or something like that) and then proceed to give me a choice of jobs, which were posted about three months before, with dozens of bids and no awards!
Yeah, the "But never mind the right job is out there for you" message is like being digitally patted on the head and being told "Awww... there, there. Chin up, everything will be alright."
I find it irksome to have to have to read that message, but I also have two reasons for liking it:
1) I prefer getting some kind of message telling me that things are actually progressing rather than none at all (because then I can move on)
2) I treat all applications as advertising