Theme app extension blocks not appearing consistently

Shopify Apps

Topic summary

Developers are experiencing inconsistent behavior with Shopify theme app extension blocks failing to load properly.

Primary Issue (mako-reactive):

  • App extension blocks stop working predictably every afternoon for 5 consecutive days
  • JavaScript files are completely absent from the page (not just failing to load)
  • Other app functionality (Remix routes, discount APIs) continues working normally
  • Switching to a different theme temporarily resolves the issue
  • Problem self-resolves the next morning without any code changes

Root Cause Hypothesis:
The pattern suggests Shopify’s CDN or asset build system may not be injecting app block assets during certain time periods, possibly due to stale references or caching issues.

Corroborating Reports:

  • One user reports blocks not working after theme changes
  • Another confirms app blocks appear in theme customization but fail to load on live pages, with scripts missing from Shopify’s CDN

Status: Unresolved. The original poster is willing to provide store access and logs for investigation of this potential platform-level issue.

Summarized with AI on October 28. AI used: claude-sonnet-4-5-20250929.
1

Hello,

I’m developing a Shopify theme app extension (part of a Remix app), and I’ve run into an unusual issue:

  • For 5 days in a row, the theme extension stops working in the afternoon.

  • The issue is not just failed JS loads — the JS files are not injected at all into the page. They’re completely absent from DevTools > Network tab.

  • However, the rest of my app (e.g., Remix routes, discount APIs) continues to work fine.

  • If I switch to another theme during the broken period, everything works again — the JS files show up. Then, the next morning, the original theme works fine again without any code changes.

This suggests that:

  • Shopify is not injecting the app block assets during certain hours.

  • The issue might be related to Shopify’s CDN, asset build system, or stale app block references that fail silently.

I’ve verified this consistently across multiple days and themes. The behavior resets daily and is triggered without any deployment on my end.

Can you investigate this as a potential Shopify-side issue with how theme extension assets are built or injected?

Happy to share store access or screenshots/logs if needed.

Best regards,

4 Likes
2

For me it’s not working after changing theme.

3

We are experiencing this as well.. Our app blocks will show in the theme customization window but not in the live pages. Our scripts are not even being loaded by the Shopify CDN.