I was able to connect my HC-05, pair it with my phone, and I can see data in the Serial Bluetooth Terminal Android App. But when I try to connect it to a certain application it says it cannot find it. Can the application force a certain version of Bluetooth? Am I missing something? Thanks.
The HC-05 modules use bluetooth 2.0. Certain apps would only be compatible with bluetooth 4.0 devices (BLE - Bluetooth Low Energy), such as an HM10 or AT09.
It could be that your app requires the device to use v4.0+. Are you able to find, and pair with the device using your android's default bluetooth device scanning/pairing features?
Assuming that your app does not require v4.0+, have you removed the connection from 'en'/'ch_pd' to 3.3v? If that was still connected (which is a required connection to enter AT command mode), then your bt module would not be able to accept incoming pair requests etc.
hope this has helped. :)