When I try to import a 25min flac file, it only show 0.085s audio length.
I am using VLC to convert flac to mp3 before import to audacity.
I use HTC 11 plus to record the flac file.
Win 10 and audacity 3.1.3
Good job finding a solution!
When I try to import a 25min flac file, it only show 0.085s audio length.
That’s a bit unusual… Invalid or “imperfect” MP3s are somewhat common and Audacity is more “picky” than most applications when it comes to opening MP3s.
I am using VLC to convert flac to mp3 before import to audacity.
I recommend converting to WAV if you are going to open in Audacity. MP3 is lossy compression and Audacity is going to decompress the file when you open it. If you want to end-up with an MP3 you should compress ONCE as the last step to avoid multiple generations of lossy compression.
Or if you want to end-up with FLAC (lossless compression) you should avoid lossy compression altogether.
I use HTC 11 plus to record the flac file.
Maybe try a different recording app. 
Thanks for reply. 