I’ve made a simple application that connects to a block through the Bluetooth dialog. It works fine but when I disconnect the block through the same dialog it crashes the application. The callstack reveals it crashes when JUCE tries to handle the disconnection of the device.
Have you tried this with the latest develop? I’ve just tried running the blocks examples on an iPad Air 2 and connecting/disconnecting a lightpad block via the bluetooth pairing dialog is working as expected. It might also be worth making sure that your block is on the latest firmware version.