Keyboard keeps changing language on input

jimpal wrote:

There is clearly a problem with Language in our new Tahoe.

I noticed that the language shown on the login page had automatically shifted to "French" instead of "US," so that apparently meant my old password (set in US) wouldn't work.

Normally when that happens you should be able to click on that icon in the top right corner and see a way to switch the keyboard back to US. Was that not possible?

I then went to Settings and Languages, with Preferred Language as English and Region, United States. With no other languages listed as alternates for selection. Now I can log into my iMac again and all is well

Good news! But the Language and Region settings normally have no connection to the keyboard layout. To make sure you have that correct, go to system settings / keyboard / text input / edit / all input sources and use the minus button at the bottom to remove everything on the list except US.

kraykov wrote:

this only happens with external keyboard when using the "Select previous input source" shortcut. Does not happen when i use the "Select next input source" shortcut, when i use the built-in keyboard, or the mouse.

What is the make of your external keyboard? Can you try a different one?

There is clearly a problem with Language in our new Tahoe.

In my case, somehow because of a Language bug, I could not log in to my shut down M4 iMac which became a brick. I noticed that the language shown on the login page had automatically shifted to "French" instead of "US," so that apparently meant my old password (set in US) wouldn't work. During my many attempts at changing the language and then startup the computer would sometimes offer up potential selections of other languages besides French. But I could not make my iMac start up again.

Some hours later, after fruitless discussions with two AppleCare guys, I decided on my own to re-install Tahoe. I then went to Settings and Languages, with Preferred Language as English and Region, United States. With no other languages listed as alternates for selection. Now I can log into my iMac again and all is well as far as that goes. I don't know whether selecting possible alternate languages will work now, but I'm just pleased to have my iMac again.

Now I wonder what will happen when Apple issues its first update to Tahoe.

I have the same issue. I'm using 2 languages - BG and US and when I switch the language it constantly switches it back, not only when switching apps, but even in the same app when using a shortcut (CMD+F for example). The strange thing is this only happens with external keyboard when using the "Select previous input source" shortcut. Does not happen when i use the "Select next input source" shortcut, when i use the built-in keyboard, or the mouse. The key combination to use the shortcut is not the issue, because i tried several different combinations. The issue appeared after upgrading to MacOS Tahoe.

Same here. Sometimes I would be typing in one language, and after a comma or quotation mark, it would automatically switch back to English. This is so annoying. I have to use two other languages besides English, especially when working, and I often realize that I am typing "Ffdadfdff Fdfsdff" because the input language has changed back to English without my involvement, out of the blue.

This is a bug. A nasty bug which should be fixed in version 26.1 or even 26.0.1. Usually, Apple releases a bug fix version within a week, but it's been almost two weeks.

It's actually for me too. After switching language I starting typing first letter is in new language and next are typed in another language. It is happens very often when first letter is in upercase.

MacOS Tahoe 26.1

What are your other keyboard languages?

Do you have this problem in Safari, Mail, Messages, Notes, and Pages?

Same problem if you are only moving between Apple apps, like notes, Safari, messages, and Mail?

Does it only happen between English and one of the others, or also between rus and el for example?

It's ZMK based. I pulled my old Logitech and it seems to be working as expected.

Same issue, Mac Studio M4 Max on Tahoe 26.1, using Logitech MX Keys S. Bulgarian and English (ABC) input sources.