shared album picture sequence wrong and not possible to change

I also was talking about the latter one. Let me try to explain more clearly:

Every album can be displayed in multiple ways, e.g. filename, capture time, rating, etc., and if it’s synced to the cloud each client app can be set to display that album using different display orders. But in addition to those fixed display orders, the user has the option to set a custom sort order (using drag and drop), so when that’s done the album will be displayed in that custom order provided that “Custom Order’ is chosen as the current display order. There is only one Custom Order per album, which of course will sync across the ecosystem so that setting “Custom Order” in any of the other apps will display that same custom order. If a custom order has not been set, using the “Custom Order” display option will show the album in capture time/date order.

The importance of this is that when an album is shared, the client will always be shown the album using the current custom order. The owner can still choose to see the album in any of the display orders, but the client can only see the custom order. Therefore, in order to ensure that the client sees the album in the way that the owner wants, the owner must pay attention to the current custom order and rearrange it as needed. As I mentioned, you can reset the custom order to match one of the other sort orders, but that is most easily done using the Share Layout Grid in the LrWeb browser app.