12 tries to get it to work. it is a timing issue. not too soon and not too late. you are likely a fraction to slow when you click it.
What timing did you use that worked? I've tried starting at 0:00:00 (maybe 0.2 seconds after the whole hour), I've tried submitting clicking captcha at that point. None of it works, it takes about 10 seconds for the page to load, it's probably heavily overloaded by bots at that time.
I just tried again: at a fraction of a second I clicked "FREE Submission", I beat 88% of the users with the captcha, but I was too late.
You're right on the situation now, probably between my last tries and yours the bot activated, maybe also Philip managed to getting an interval where the bot wasn't active or so. After failing 4 times I just gave up and put my browser on recording with a refresh rate, I'm on fiber, with an extremely low latency, the page loads in 1 second, so I only managed with it refreshing at 59:59, 00:00:01, 00:00:02 to catch a glimpse at 5 free once.
What's even more interesting is that the number of so called accelerate tractions increased by 11 in the meantime, really weird since a long time ago they were only moving this when the block was mined, I really need to wait for a few more hours and check it again to see what's really happening but I'm starting to think Viabtc is no longer truly offering 100 tx per hour