Unfortunately that is not a very useful bug report. It implies that the problem only occurs with FLAC files, but the default behaviour in Audacity is to always copy the data into the project, so the original format of imported file is irrelevant unless the user has changed the default import behaviour. Also, they don’t say whether the waveform looks normal. They don’t say whether they are using PulseAudio, Jack, or plain ALSA. They don’t say if the problem occurs with other file types.
Perhaps you could fill in the missing information.