Closed Captions decode but stop on DeckLink SDI

[Brian]

Summary of the bug: Closed Captions decode properly on Decklink SDI until the http/HLS stream provider drops captions during commercial breaks, after that happens, the captions never return back to working, unless you restart FFMPEG. The same issue does not happen directly streaming in VLC or if I use FFMPEG to stream the HLS to a UDP player or directly to a file (like the one I am providing).

I believe this issue is only related to the Decklink output. The Decklink output continues to display the idle caption bars on line 21/O even though the captions have returned in the stream.

I have a recording sample that triggers this action on Google Drive: ​https://drive.google.com/file/d/1d8ts13PqRDp2mNR9E7W_cR9ztkBNzLUk/view?usp=drive_link
How to reproduce:

./ffmpeg -i AMGCCtoNoCCb.ts -filter:v fps=30000/1001 -f decklink -top 1 -s 1920x1080 -r 30000/1001 -ar 48k -ac 2 -vcodec v210 "DeckLink SDI"
ffmpeg version N-111626-g0ba719f726
built with gcc 9 (Ubuntu 9.4.0-1ubuntu1~20.04.1)
configuration: --prefix=/root/ffmpeg_build --pkg-config-flags=--static --extra-libs='-lpthread -lm' --bindir=/root/bin --enable-gpl --enable-libzvbi --enable-libfdk-aac --enable-libass --enable-libfreetype --extra-ldflags=-L/root/ffmpeg_build/lib --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-static --disable-opencl --enable-libx264 --enable-postproc --enable-openssl --enable-decklink --enable-small --enable-libklvanc --extra-cflags=-I/root/Decklink_SDK/Blackmagic_DeckLink_SDK_12.2.2/Linux/include --extra-ldflags=-L/root/Decklink_SDK/Blackmagic_DeckLink_SDK_12.2.2/Linux/include --enable-nonfree --disable-debug