Hey Seth,
Thank you for the detailed report and the clear reproduction steps. I understand that in the Cornerstone builder, an autoplaying video placed inside a closed Modal (and likewise Off Canvas or Dropdown) starts playing as soon as the builder loads.
We have reproduced this on Pro 6.9.6 / Cornerstone 7.9.6. In the builder preview, a Modal containing a Video element (Embed type, YouTube iframe with autoplay=1) loaded the video about 1.4 seconds after the preview loaded, with the modal closed. The video played through to the end without the modal ever being opened. This happened with Dynamic Rendering turned on, and your analysis is correct: in the builder, the modal’s content is mounted straight into the closed modal rather than being held back until it opens, so the Dynamic Rendering setting is not applied there. The live site is not affected. With Dynamic Rendering on, the same modal’s content is not loaded on the front end until the modal is opened.
Keep Dynamic Rendering enabled on the live site – Select the Modal (or Off Canvas / Dropdown) and make sure Dynamic Rendering is on. This prevents autoplaying videos from loading or playing for visitors until the modal is opened. Without it, iframe embeds are present on the page from load and will autoplay on the front end as well.
Workaround while editing – Until a fix is released, remove autoplay=1 from the embed URL while you work on the page in the builder, and add it back before you finish. This stops the video from playing in the background each time the builder loads.
Bug report to our developers – We have passed this issue to our development team with your reproduction steps, and your suggestion to defer closed toggleable content in the builder until it is opened. We cannot give a release date, but please keep an eye on the changelog for a fix.
Best Regards.
| # | Наименование новости | Тональность | Информативность | Дата публикации |
|---|---|---|---|---|
| 1 | Builder preview loads and autoplays media inside closed Modal / Off Canvas / Dropdown content | 0 | 6.01 | 11-10-2026 |
| 2 | Table element - element failed to render error | 0 | 25.21 | 14-10-2026 |
| 3 | Trigger a Success Modal without redirects or closing the active modal in Forms | 0 | 6.93 | 09-10-2026 |
| 4 | Previews not loading using Cornerstone - sudden issue | -2 | 3 | 28-06-2026 |
| 5 | Cornerstone can't load because of social media link?! | -5 | 2 | 27-06-2026 |
| 6 | parametric bug | 0 | 42.08 | 03-08-2026 |
| 7 | Trigger a Success Modal without redirects or closing the active modal in Forms | 0 | 4.76 | 09-10-2026 |
| 8 | Feature request: bottom sheets for mobile views (new toggleable type) | 0 | 9.54 | 12-10-2026 |
| 9 | Thread got closed while still waiting for an update | 0 | 5 | 13-07-2026 |
| 10 | Page Builder update breaks existing SiteOrigin layouts | -2 | 3 | 12-07-2026 |