Switching to a tab in a second Zen Window shows "New Tab" and doesn't load the tab (shows a blank window)

[rabbly]

Preliminary Checks

• I have read and understood the important section above.
• I have searched existing issues and avoided creating duplicates.
• I am not filing an enhancement request.
• I have checked that this issue cannot be reproduced on Mozilla Firefox.
• I have checked that this issue can be reproduced once I removed all my Mods and Custom CSS.

What happened?

When I have two Zen windows open, and try to open a tab in a separate window, it sometimes renders as "New Tab" and doesn't load. This doesn't happen all the time - but seems to occur after using Zen for some time (e.g. 30 minutes). I have to close and re-open the Zen window to fix it.

Expected behavior

Clicking on an already open tab in another Zen window should load the tab

Actual behavior

Tab stays with the title "New Tab" and doesn't load.

Note: this happens on many different web pages - does not seem to be isolated to any individual site.

Steps to reproduce

1. Open first Zen Window
2. Open various tabs
3. Open second Zen Window
4. <keep using Zen, as this issue seems to happen over time>
5. In the second Zen Window, select one of the tabs you had opened in the first Zen window
6. See that the tab doesn't load, and stays named as "New Tab"

I have to close and re-open the Zen window to fix it.

Screenshots and videos

Version

1.19.5b

What platform are you seeing the problem on?

macOS - aarch64

What component is this issue related to?

Tabs

Relevant log output if applicable

[mr-cheffy]

Could you please show a video on how to reproduce this? Or at least open up logs via cmd+shift+J and send a screenshot?

[rabbly]

Here is a video showing the issue.

Zen.Tabs.over.Windows.Bug.2026-04-01_09-06-08.mov

[mr-cheffy]

Could you please open the logs with ctrl+shift+J and show me a screenshot?