Feature Request:
When a locator range is set in the project window, it should dynamically follow any timeline adjustments.
Reasoning:
When I am starting a new track, there comes a point where I audition various different project tempos to make a decision on what tempo sounds the best. However, every time I adjust the project tempo I have to manually re-adjust the locator range to re-align it back with the timeline correctly. I can’t think of any circumstances where this current behaviour is desirable.
If you have your primary time display set to time of some kind then naturally locators are locked to the time you placed them.
If you set your time display to bars and beats then locators are fixed to the bar and beat etc. Regardless of tempo.
(Providing your track is set to musical time base of course).

So why is my locator range not locked ?
Well, it might be possible to get a better insight if the screen shot was not the size of postage stamp. 
If I were to guess, you might have your settings at Time Linear, try it as Bars+Beats Linear. Access this by right clicking on the time display. But even doing that, it should not display this effect seen in your video.
But joking aside: Cannot see your project primary time base settings at all, although it appears your main project time is bars and beats it is very difficult to tell.
Please post a better-quality screen grab. Help us to help you.
It would also help if you added a couple of rulers. One set to Bars and Beats and one set to one of the time options. Then repeat the tempo changes and let us see what is happening.
If you like, as a last resort, you can temporarily remove Defaults.xml (there is no system info provided by you, so I presuming it is Windows):
%appdata%\Steinberg\Cubase 15_64
- Close Cubase
- Go to the link I posted above
- Move that file to your desktop
- Start Cubase
Does it change the behaviour?
You can always restore it by closing Cubase and moving that file back.
I have tried both “Time Linear” and “Bars+Beats Linear” and neither of them lock the locator range in position.
Are you saying that the locator range locks in place for you in Cubase 15 ?
Yes. It works as expected, (the gif may be glitchy, but you can see it working):

As mentioned, if you are sure you have settings set as they should be, try the default.xml method above.
Interesting. I will have to investigate further. Thanks for letting me know.
Just try the steps above with the defaults.xml
You will find it here:
%appdata%\Steinberg\Cubase 15_64
Just copy and paste that link into your file browser and follow the other steps I posted.
I seem to recall somewhere that someone had this issue a while ago, but not with C15.
It only takes 2 minutes, and you can easily restore it if it messes things up for you.
Someone else may have better suggestion than me.
Perhaps also try with fresh project too, if that works OK then you can import your tracks from the other project to the new one.
You are correct. It totally makes sense now.
My Cubase 15 trial license recently expired and I am back to using Cubase 13. I just assumed this behaviour was still present in Cubase 15.
I will mark this thread as solved now. Thanks for your help.
My pleasure, it would be good to know if this is actually an issue though, if you get a min to check it out later it might be helpful.