Another Day, Another Challenge, Another Opportunity and Another Solution !!
My suggestion. (Might/Might Not Work)
1. Upgrade B4i to version 6.00
2. Remove the "grayed" app (on your new device) for a fresh install to take place (in other words - delete the app)
3. Go to your B4i IDE
4. Click on Tools-->Build Server-->Server Settings - You will arrive here:
5. Switch to 64-bit and try installing the bridge app again.
You see the only clue that I could get is that you have previously installed on older devices (eg. iPad2 - which is 32-bit) and that this setting could possibly be on 32 bit - your newer devices require 64 bit to run or they will throw the error you mentioned.
Have an Excellent Day !!