So - answer from Lexus - you can only use the app to remotely unlock the car if you used the app to lock it earlier!
This is ridulous. Firstly, drivers will rarely know in advance that they might have a need to remotely unlock the door, usually this function might be needed when a passenger unexpectedly has cause to return to the car without the driver, i.e. to deposit shopping, to retrieve a forgotton item maybe, etc. when the driver has perhaps had to be elsewhere, i.e. at a seperate appointment, etc.
No one is going to get into the habit of routinely locking the car via the app to cover such unexpected / rare circumstances considering the fact that rather than simply exiting the car and pressing the door handle, to lock it via the app will involve getting ones phone out, opening the app, pressing the remote lock button and waiting some 60-90 seconds for the app to connect to the car and hopefully lock the doors (I say "hopefully" because many times I try to use this app I get a message telling me "there was an error processing your request, please try again"). It is simply far too cumbersome and time consuming.
I know that the level and capabilities of the tech on Lexus vehicles is sadly way behind that found on other makes but the ability to remotely unlock the car irrespective of how it was locked is surely not beyond the skills of Lexus programmers? My previous BMW's and even my two previous Ford Focus's remote opening apps allowed it.
Yet another Lexus failing, frankly there are far too many for an alleged "luxury" brand Takumi spec. Lexus product developers really need to rent a BMW for a week or two to see how tech should really work.