There's been something strange happening lately. Either the girls I'm messaging are getting their memories wiped, or some magic spell has been casted on me. These examples I'm about to explain are from Costa Rica.
There have been instances where things are going well in the conversation (good investment on the girl's behalf), then I go for schedule or meet up text by saying "We should split a bottle of wine on my romantic balcony" or after she gives me her schedule I say "how does Sunday work for you?". Then afterwards I get no reply.

About 2-3 days later I message them with "If you're too nervous I'd understand" or "Thinking very hard I see", and they reply with "?" or "What do you mean?" or "Huh?" or "Thinking about what?".

These responses make me think that they're either playing dumb, or they legit got their mind erased. Granted, another reason can also be that they live extremely busy lives, so they may forget the whole topic at hand since the beginning, but either way, the question I asked is the second thing that comes up (whatsapp), so they don't need to scroll through the whole conversation to see what I'm referring to.
Is the correct way to handle this situation by replying with the same level of confusion, such as "Oh?" or "Hmm?", or should I do something else?