Cannot set custom descriptors

Interesting. I tested newer 2v16 build on 52832, just bare Espruino and the example works fine - get all parts in order. I have updated Bangle to 2.17 release, updated all apps and it still does this. Good for verifying this is also Serial Bluetooth Terminal app for Android, one can select custom characteristics for input/ouput when connecting to device (hold on the name, there is menu). I'll test 52840 dongle too.

EDIT:
The 52840 dongle does it too so it is maybe related to SDK12 vs SDK15. With the dongle I can connect console over USB and keep it there while connecting over bluetooth so I have added print(i,E.toString(Uint8Array(val,i,(l>len)?len:l))); to the while loop and I can see it printed on console just fine while I get just a subset of those lines over BLE. Also the nordic uart is not used so there are no extra notifications due to the console and still it does not work

Connecting to Dongle c56e.
Found 4 services:
#00: 0x1800 (GenericAccess)
#01: 0x1801 (GenericAttribute)
#02: 6e400001-b5a3-f393-e0a9-e50e24dcca9e
#03: 0x190A (6410)
BLE: set #03
Selected service 0x190A (6410).
#00: 0x2 (2)      N
#01: 0x1 (1)     W
BLE: subs #00
BLE: write #01 process.env\n
Value changed for 00000002-0000-1000-8000-00805f9b34fb: "STORAGE":393216,"SE
BLE: Value changed for 00000002-0000-1000-8000-00805f9b34fb: torage,heatshrink","
BLE: BLE: write #01 process.env\n
Value changed for 00000002-0000-1000-8000-00805f9b34fb: {"VERSION":"2v15.54"
BLE: Value changed for 00000002-0000-1000-8000-00805f9b34fb: ,"GIT_COMMIT":"5345b
BLE: Value changed for 00000002-0000-1000-8000-00805f9b34fb: 840Dongle","RAM":262
BLE: Value changed for 00000002-0000-1000-8000-00805f9b34fb: 10a7","CONSOLE":"USB
BLE: Value changed for 00000002-0000-1000-8000-00805f9b34fb: AM_BASE":536882880}

in the console I see twice this

0 {"VERSION":"2v15.54"
20 ,"GIT_COMMIT":"5345b
40 5f71","BOARD":"NRF52
60 840Dongle","RAM":262
80 144,"FLASH":1048576,
100 "STORAGE":393216,"SE
120 RIAL":"05950628-5644
140 10a7","CONSOLE":"USB
160 ","MODULES":"Flash,S
180 torage,heatshrink","
200 EXPTR":406704,"APP_R
220 AM_BASE":536882880}