Possibly unrelated to the iOS 14 update, but I can no-longer receive calls on my mobile number unless my iPhone is switched off, then my Apple Watch rings... otherwise 'The person you are calling cannot be reached at this time'. I can make calls without issue. 

Anyone on Spark with an Apple Watch Cellular with one number able to check they can still receive calls? 

(Yes I have logged a fault with Spark but they didn't seam to understand the eSim Apple watch product)