BLE Uart increase 20 byte limitation


Currently I am experiencing some problem getting the NUS to send a TX notification of more than 20 bytes to the central (which is an old custom android application). From the logs on the android application side, it looks like my messages are getting cut off after 20 bytes. I have already increase the NRF_SDH_BLE_GATT_MAX_MTU_SIZE  to 240 and also the MESH_GATT_PACKET_MAX_SIZE to 240 since I am running the NUS alongside Mesh, yet the above issue still remains. Are there any suggestions for this?

Some background:

- The problem is definitely not the android application, because it also used to connect with a raspberry Pi BLE peripheral running the NUS and the raspberry Pi can send notifications of well over 20 bytes just fine

- This is probably unrelated, but for the Mesh side I use PB-Gatt for provisioning and have proxy enabled. So this is a BLE-and-Mesh coexistence kind of application. The mesh proxy service runs alongside the NUS. The mesh part of the software runs perfectly fine. 

- Basically what I'm trying to do is to make the my current software backwards compatible with an old android application that has proven to work with a raspberry Pi BLE peripheral also hosting a NUS. 

Thanks in advance