It can be for various reasons from duplicate posts/accounts some links included etc the spam/security filter works in the background and where it feels necessary acts, at times it’s because you may of pressed submit twice but the filter reads it as a duplication so doesn’t allow, other times it may not recognise a valid email address or conflicting accounts as not signed in users etc etc, I’ll check the spam file to see, but as it reads and reports using Binary and code it may not help unless We see an issue ourselves .
Sign out and back in again making sure your email is correct as if incorrect it won’t leave a report just refuse post, if a none signed in user it is more sensitive to post and links, it can be over sensitive at times but overall does a great job keeping us all safe in the background.