Video, sound, and caption problems

Previews don't move, videos play without sound, or captions and subtitles don't appear.

Thumbnails don't play previews

Preview videos is Off — play on tap by default for Stories, Carousel, and Grid. Change it on the widget's layout tab, under On the thumbnails. See Preview videos.
Phones in Low Power Mode or with data saving on often block autoplaying video. Shoppers then see the poster, which is normal.
Images never animate.

Open muted in Settings → Fullscreen player, or Start with sound off on the widget's Player tab, is on. Either one mutes the player.
Browsers, especially on iPhones, can block sound until the shopper taps. The video then plays muted, and the shopper taps the speaker for sound.
The mini player has no sound button. Shoppers expand it to change the sound.

If the file was deleted from Content → Files in Shopify, the clip can't play. Remove it from the widget, delete it from the library, and add the file again.
If the widget won't save, with Some files are still processing, one of its files isn't ready or was deleted. Wait a moment and save again. If it keeps happening, remove that clip.
With Settings → Videos → Playback mode on Quality, shoppers get your original file. Some browsers can't play some formats, such as HEVC .mov files from iPhones. Switch to Performance, which plays MP4 versions Shopify makes of each video.

Is the clip a draft? Draft clips stay in your library but are hidden from widgets. Open the clip in Video library, set Status to Active, and click Save. Foxr updates your widgets for you. Allow a minute or two. See Status: Active and Draft.
Is the whole widget hidden? A widget hides itself when fewer clips than its minimum can show. Drafts count against it. The minimum is Show only with at least in the widget, or Minimum media to display feed in Settings.
Is it a Product page widget? It only shows clips tagged with the product being viewed. See The Product page layout.
Was the clip deleted from the library? Deleting a clip takes it out of every widget.

Captions are the short text under Carousel and Grid cards, over Product page clips, and above the product card in the player.

Is a caption switch on? Turn on Player → Show captions in the widget, or Show media captions in Settings for the player only.
Does the file have alt text? Captions come from the file's alt text in Shopify Files, not the library Caption field. The library Caption is only used as the description in your search engine data. Add alt text under Content → Files in Shopify.
Did you save the widget after changing the alt text? Widgets pick up new alt text when they're saved. Saving a change on the clip's own page refreshes its widgets too.
Stories and Pop up don't show captions on thumbnails, only in the player.
Captions under cards are invisible on a dark background? They use the heading's Text color, black by default. Text color only shows once Heading text is filled in: type a heading, set the colour, then clear the heading if you don't want one. The colour is kept. See Heading and clip order.
Product page widgets save with captions off at first. Turn on Player → Show captions and save.

Subtitles only show for videos, in the player. They don't show on thumbnails or cards.
New or changed subtitles take up to about 10 minutes to reach your storefront. A shopper who watched the clip in the last hour may see the old version one more time.
Check the CC button in the player isn't switched off.
Make sure the video page shows a cue count under Subtitles (WebVTT) and that you clicked Save. See Subtitles.
The CC button only appears once the player has loaded the clip's track. If a video has subtitles but no button, wait a few minutes and reload.