Sorry for the delay in getting back to this thread. All seems to be working today just as it should. vanadium's suggestion of toggling the setting "Tweaks | Top Bar | Application Menu" was all that was needed. Testing against a live session of yesterday's build of 18.10 I previously saw many more prompts to restart my session than I when running the live session. These prompts no longer appear when I open Tweaks but only when I toggle the Application Menu setting. I don't know whether there is a bug here, a clash with an extension or whether it was down to a simple human error. Anyway, I'll mark this as solved on the basis that the simple toggling a setting was the correct solution even though for some unexplained reason it didn't work first time. Thanks to all that replied.
This just helped me tremendously, thanks!
18.10 has been released. Thread closed
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