nrf52 "pairing took too long" with iPad - HID keyboard device

[MattFL]

Please point me in the right direction if you can, I'm stumped.  My project is based on the app_hids_keyboard sample, using the pca10040 board (nrf52832) and SDK 14.2, soft device s132.  It pairs great with Android devices, and some iOS devices. But on my customers iPad he frequently gets "Pairing Unsuccessful Pairing took too long".  After enough fiddling it will eventually connect, but he gets this error more often than not.  I'm told he is using the latest iOS and that it's an iPad mini 4 running iOS 11.3.1 (the latest).  Are there any known issues between the Nordic and Apple devices?  

Edit --> I reproduced the issue here with an older iPad.  What is actually happening is the Nordic device will not re-connect to iOS unless the bonds are cleared.  If the bonds are cleared, iOS reconnects almost instantly.  But without clearing the bonds, iOS won't reconnect reliably.  Does this ring bells to anyone? 

[run_ar]

What is actually happening is the Nordic device will not re-connect to iOS unless the bonds are cleared.  If the bonds are cleared, iOS reconnects almost instantly.  But without clearing the bonds, iOS won't reconnect reliably.

Do you also clear the bond from the iOS device? Do you find your device in the iOS bluetooth device list?

[MattFL]

I did nothing to the device on iOS and it remains in the device list.  The only option in iOS is to "forget" the Nordic device.  If I "forget" the device in iOS then I need to re-pair the two.  If I do nothing in iOS and power-off the Nordic, then clearing the bonds on the Nordic when it powers up allows them to reconnect right away.  If I don't clear the bonds on the Nordic device then the two don't reconnect reliably.  Unfortunately all of my Nordic devices have now been sent to my customer for proof of concept testing, depending on how that goes I will hopefully have some more devices here that I can work with.  Once they are connected they seem to work fine, it's just the connecting part that needs some work.  

[run_ar]

Does this happen all the time with a "failing"device? Have you tried restarting the iOS device? Which iOS devices work and which does not? Are you able to recreate this with any of the SDK examples? I did some testing with the HID example, but iOS reconnects automatically.