Are your other accounts all Friendica instances, or others as well?
mostly friendicas, indeed all my recent test posts were sent only to my other friendicas, whereas iirc maybe one or two of my original tests, the other day, were also sent to my Masto account.
make a difference whether you use a direct mention or the Messages menu?
pls indulge me here. atm it's late & i'm tired, quite fuzzy, & i'm struggling to grasp what each option is that you're asking. immediately after i first registered this new account, i tried various combos of test-post creation, but by now there's too much water under the bridge for me to remember clearly what's what. otoh my most recent test-posts, like the one at the top of this thread, i created simply by clicking the "New Post" button at top rhs corner of the Network page, then in the composition drafting box i typed in the account addresses i wanted to send to. does that make sense?
mentioning someone in a private message does not work
if you mean this:
then not only did it not work for me here, but iirc it rarely or maybe even never worked for me in any of my other friendicas, both still-active ones, & older ones now deleted. tbh i always found it so unreliable as to not really bothering any more with it... maybe it's a general friendica code bug?
sending a direct message using the Messages menu
atm it's 90' after midnight, but late yesterday morning you sent me this DM...
...& i was able to reply to you, so i presume this means we can confidently say that this specific component is working well?
if you don't mind, i'd like to now mention an additional issue that troubles me with my new account here. i prolly would have raised this with you another day anyway, except i now wonder if it might also be another part of a larger problem with the server?
the same day i created this account i tediously manually Followed all the numerous hashtags i follow [~100] & then created my custom Channels for those tags. for reasons i still don't yet understand, in this account those tags searches [& thus also the Channels] often fetch nothing, or otherwise much less than my identically-setup current daily friendica, @Droppie [opensoc] . this disappointment might be entirely unrelated, but i thought to mention it here just in case it might be another facet of some broader issue with your server's current networking / fediversing...?
off to bed now, bye.