LG Rolly Keyboard pairing problem with IOS.

My LG Rolly 2 keyboard can pair with my android tablet and Macbook pro without a problem but it does not connect normally with my ipad and iphone running ios12.1.3.

When it connects with iOS, the on-screen keyboard does not disappear. Whenever it disconnects (e.g. ios sleeps), it can't automatically reconnect when iOS powers up. Every time I have to unpair and re-pair to connect the keyboard.

I have tried numerous strategies including Bluetooth on-off, pair/unpair/pair, reset network settings, bluetooth reset, device factory reset and iOS update. None works.

It wasn't a problem when I was using iOS 11. Does anyone of you have this problem and is there a way to get it work? Thank you!