Status/mentions_timeline endpoint doesn't return all mentions



Hello, Social network aggregation tool developer here!

I’d like to report a problem that occurs lately when using mentions_timeline endpoint.
It seems that not all mentions are accessible through this endpoint when using certain account.

Using statuses/show endpoint for certain id shows that this mention exists and “user_mentions” field contains right user for which mentions were fetched

What could be the cause? Is this some king of bug on Twitter’s side?