You are told: an async FIFO bridges a fast writer and a slower reader. Occasionally, and only under bursty traffic, the reader sees the empty flag asserted while the writer insists data was available. The reader idles, throughput dips, and the flag clears by itself a little later. Data is never corrupted and never lost: every written word is eventually read exactly once. Both clock frequencies are as specified, and reset sequencing is "the standard one", which nobody can produce in writing.
Three details carry the diagnosis. First, the flag is wrong transiently and self-clears: the comparison saw a stale or torn write pointer, then caught up. Second, data is never lost or duplicated: the storage and the eventual pointer values are correct, so only the crossing timing of the pointer is suspect. Third, burst-dependence: pointers move fastest under bursts, which is when multi-step Gray transitions and synchroniser latency hurt most. The prime suspect is the write-pointer crossing into the read domain: its encoding, its synchroniser, or the comparison that consumes it.
A logic bug in the comparison would assert empty deterministically for a given pointer state; a transient that clears as synchronised pointers catch up matches crossing latency or a torn sample that later resolves.