cannot upload to arduino leaonardo anymore with cosmic

Hi all,
odd issue and I would like to know if I am the only one with this. I have been uploading sketches with arduino 1.8.6 on my linux box (ubuntu 16.xx,17.xx and 18.04) with no problem (uno, mega and leonardo).
Now since I upgraded to ubuntu 18.10 no joy for leonardo anymore! I am still able to upload to Uno and Mega though.
I did not change the arduino toolchain at all, only the rest was upgraded. I suspect a problem with the new CDC driver.
In any case this is the log:

avrdude: Version 6.3-20171130
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch

System wide configuration file is "/home/emmanuel/.arduino15/packages/arduino/tools/avrdude/6.3.0-arduino14/etc/avrdude.conf"
User configuration file is "/home/emmanuel/.avrduderc"
User configuration file does not exist or is not a regular file, skipping

Using Port : /dev/ttyACM1
Using Programmer : avr109
Overriding Baud Rate : 57600
AVR Part : ATmega32U4
Chip Erase delay : 9000 us
PAGEL : PD7
BS2 : PA0
RESET disposition : dedicated
RETRY pulse : SCK
serial program mode : yes
parallel program mode : yes
Timeout : 200
StabDelay : 100
CmdexeDelay : 25
SyncLoops : 32
ByteDelay : 0
PollIndex : 3
PollValue : 0x53
Memory Detail :

Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
eeprom 65 20 4 0 no 1024 4 0 9000 9000 0x00 0x00
flash 65 6 128 0 yes 32768 128 256 4500 4500 0x00 0x00
lfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
hfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
efuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
lock 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00
signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00

Programmer Type : butterfly
Description : Atmel AppNote AVR109 Boot Loader

Connecting to programmer: .
Found programmer: Id = "CATERIN"; type = S
Software Version = 1.0; No Hardware Version given.
Programmer supports auto addr increment.
Programmer supports buffered memory access with buffersize=128 bytes.

Programmer supports the following devices:
Device code: 0x44

avrdude: devcode selected: 0x44
avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e9587 (probably m32u4)
avrdude: reading input file "/tmp/arduino_build_164818/RR-duino.ino.hex"
avrdude: writing flash (18572 bytes):

Writing | avrdude: butterfly_recv(): programmer is not responding
avrdude: error: programmer did not respond to command: write block
***failed;
***failed;

repeated a lot and then several:

avrdude: Error: butterfly programmer uses avr_write_page() but does not
provide a cmd() method.
*** page 127 (addresses 0x0000 - 0x007f) failed to write

with different page numbers

BTW I can still upload sketches to my leonardo on another linux box, but first I have to reflash the bootloader (that I can do on the problematic linux box via a tinyUSB !!)
Anyone could help pls?
TIA
Manu