“Couldn't find the seeked keyframe in this chunk” since 2.86

[general]

Hello, everyone.

Recently, I couldn't resume any download tasks, only to get endless 
warning message "Couldn't find the seeked keyframe in this chunk". It is 
very likely that the problem comes with get_iplayer 2.86, before this 
version I could resume almost every incomplete download tasks after this 
warning “WARNING: Stream does not start with requested frame, ignoring 
data...”  The former warning seems from rtmpdump, which remains the same 
version as with get_iplayer 2.85. Could anyone give me any cues?

Best regards,
Zhe