... letting her know that you're sorry you didn't sync up on plans and since you didn't hear back from her in X days you made other plans is fine. She does have plenty of time to fill that time slot.
Whether or not it gets you on a blacklist is up to her. I don't think a reasonable person would blacklist someone for that, but unfortunately not everyone in this world is reasonable. 
There are so many reasons she may not log into a site, perhaps she started a profile on a site that hit a vein and she's working that. Time off, not needing to bother with every site.
Since it can not happen for so many reason it's wise to shop for a plan B and even C just in case, from the start.
Regarding p411, i' m relatively new to that site, and at least right now, it's very ineffective so it hasn't become a priority to check in there I've gotten a handful of folks from there, but I don't think any of them started there. They may find me here then go to P411 to email me, which is great because then I can look at the OKs that they have so it's a good start.
When I leave money on the table through disorganization, I know that is my loss, but not his fault!
If I havent' gotten back to him about it in a bit, it is nice when I get an email that says he will need to make other plans if it looks like this isn't happening. But more often what happens is when I finally get back to them the reply is often that they made other arrangements. Fair enough!
I cannot imagine blacklisting someone for that. NCNS yes, but me dropping the ball(s) and losing the opportunity, that's the cost of doing business badly! And that happens for lots of reasons, it doesn't mean she's sketchy or on drugs or crazy or lazy.
Lastly can you think of anything that might have soured her to the idea of a date with you? Good luck! Hope you find a great provider and have a wonderful time!
Over the years there’s been times I wanted to meet a provider but for some reason it didn’t happen. Ranging from I started feeling cold symptoms prior to the play date and canceled to simple schedule conflicts. I have however made appointments to meet these women months later. She may not be active at the moment, but in a couple months she may be logging in regularly and new reviews may start popping up. That’s quite common.
As long as you don’t become a creeper and do move on to someone else after a failed attempt to connect with someone, they will be happy to see you when they’re active again, provided you meet the screening requirements. That’s the beauty of the hobby. Unless she retires, you will more than likely see her by spring as long as you keep an eye on her profile from time to time and are aware of when she’s active again.
