I have a sync problem with closed captioning as well. The other day I turned on my TV it was tuned to BBC America and the "Princess Bride" was on, but the captioning was from the previous show "Star Trek The Next Generation". "Princess Bride" had started 17 minute earlier, about 5 minutes later the dialog from "Princess Bride" finally started. This is a very serious breach of the FCC rules, which says the dialog much coincide with the spoken words. See https://www.fcc.gov/guides/closed-captioning for details It is unlikely to be the TV if the cable box controls the CC. The easies way to display the CC is to include it in the image. I just check my TV it has CC abilities in antenna mode but not in HDMI mode, which means the cable box must send the CC via the image not as a separate CC signal, when using the HDMI connector. My guess is the software keeps the dialog visible for a fix length of time and adds the new dialog to a queue, instead of deleting the old dialog when the new dialog arrives, as a result the queue builds up over time. 17-22 minutes worth of dialog is a very large queue. In the mean time, until the CC part of the software is fixed, changing the channel does seem to delete the queue, so every commercial change the channel to resync the CC.
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