I have been on this website for 1.5 years and I know exactly what you are talking about. Finding language partners is hard for a variety of reasons.
Just like how people sign up for a gym membership, and pay for the gym, but never actually go to exercise...it's the same here. A lot of people say that they want to learn a language, and they feel better when they join the website, but when it is time to actually practice with a stranger, they change their minds.
With language exchanges, it is also voluntary for both sides. Because neither person is paying money for a lesson, they feel no obligation to do the language exchange. They change the time / date frequently.
Finally, a lot of women receive tons of messages from guys who want to date them, and they are tired of it. And most guys want to find a girl for language exchange, not a guy. So basically, both girls and guys don't want a guy.
My suggestion is just to send messages to tons of people (30+ or 40+), and make it interesting and show that you are serious about language exchange. Or, you can pay for lessons, which is what I do most of the time.
Right now, I do a mixture of both language exchange and paid lessons. I found 3-4 teachers that I really like, and 3-4 language exchange partners who are serious enough that they actually video-call me to practice 1-2x per week. It took some time and patience, though.
Here is a helpful discussion about finding partners.
Ask yourself if your profile looks interesting to other people and choose you to be a language partner.