Sometimes when I have cargo, I can’t recall all the probes I sent out. The usual solution is to dump cargo and try to recall again and 1/4 times it doesn’t work.
This guy’s problem sounds almost exactly like mine… and normally I’d just look and be like “oh that guy had my problem I’ll just use his solution” except there wasn’t one at the end of the thread!
I use probes A LOT and I’ve not had any of them disappear on me for quite some time and the last time it happened it had an obvious reason. Perhaps in your specific situation if your cargo is completely full it might be an issue but since that is not something I run in to I wouldn’t know. The thread you linked doesn’t talk about that at all so it’s not logical to assume it’s the same situation, if that is even more than just people being ignorant.
I’ve had probes disappear on me a few times as well. On one occasion it was definitely downtime because I must have left them in space when downtime hit. Other times I wasn’t even logged in at DT and had not logged off in space but afterwards I noticed that I only had 16 instead of 24 probes in my cargo. In neither of these cases was my cargo ever completely full which could have prevented the recalling of the probes.