You still get them, just very random. Also keep in mind that your chest drop rate is reduced considerably after beating a campaign's areas for the first time.

Thanks for getting in touch.

The chest animation toggle just removes the long scene when a chest drops in favour of showing the small box in the top-right corner in the web version, and shortens it in the mobile version.

It doesn't affect the odds of your Jeweled chest conversion.

You need to be killing a boss for the first time in a reset of the world (idling on a boss area doesn't get you more chests), need to be winning a silver chest, and need the game to generate the odds that it upgrades.

Depending on how many boss areas you clear in a week, you could see no Jeweled chest upgrades in a week.

Or you can be having a really long dry spell. Each chest win is a unique chance to get a chest. There is no pity timer on getting an upgrade.