I don’t believe it was lost at all. Josiah stashed it in a secret place prepared by Solomon, on or near the Temple.
When Jeremiah returned, he didn’t want it returned to its public place, or wasn’t sure it could be retrieved from its hiding place. Wishing to reassure people the rebuilt Temple would be valid without it, he proclaimed (Jer. 3) that it would not be remembered.
The Axum story could simply be a gold plated chest one king might give to another, and might date to Menelik. Gold likely stripped off it by now.
“I don’t believe it was lost at all. Josiah stashed it in a secret place prepared by Solomon, on or near the Temple.”
That apparently fits with Jewish tradition and is what a number of archaeologists think is possible. Somewhere under the Temple Mount itself is a possibility.