I have an ASIN that was steady at 16000 sales rank.

i woke up this morning to the asin having no sale rank at all.

i ask amazon for help and they said this...

Hello from Amazon Selling Partner Support,

We understand your concern is regarding missing sales rank for the ASIN B0BXJYXXYC.

We regret the inconvenience caused to you. Please let us assist you with this.

Please be informed we have checked and found that all browse node assignments have been filtered. We use ASIN ............ for determining the assignments. As this ASIN doesn't have any eligible browse node assignments, this ASIN is ineligible for any sales rank (main store rank and category sales rank).

How did i lose eligibility from yesterday to today?

I have looked in my edit menu sections and my nodes are assigned to where they should be.

Can somebody please advise how i can fix this problem please?