Broken NUS after iOS 10 upgrade

[Tim]

After upgrading to iOS 10, I have been unable to successfully interact with my device using the NUS. I used to use the NUS to communication with the device and retrieve stats. For example, I would send a "T" message to the device and it would respond with some information on the temperature of a couple of thermistors.

Now when I try to send a "T" this is all I see:

Before it used to also show the message that was sent. Now it doesn't show that a message was sent. The following image is taken from two months ago. This is the behavior that I can no longer reproduce but would like to see.

Also, I have noticed the appearance of Optional("...") in interactions since the upgrade. For example, in the first image it first says 'Connecting to: Nordic_UART ...' but then it later says 'Connected to : Optional("Nordic_UART")'. Why has this appeared?

[Tim]

Using the sniffer, I was able to see that the messages are being sent correctly, but my iPhone is just not sending the message I specify. For example, When I try to send the message "Test" as it results in a green notification on my iPhone '0x17582964 sent.' similar to the message in the third picture. This is indeed the message sent to the device as sniffed using Wireshark/Nordic Sniffer. Seen by the sniffer, the device in turn responds with the proper "NOT OK" message that it is programmed to, but all I see on my phone is 'Optional(6 bytes) received' as another green notification.