Cannot find USB serial ports on 2.5.0-SNAPSHOT

Hallo,
in a binding I am developing i was able to find USB serial ports, but now after moving to openhab-core 2.5.0-SNAPSHOT I cannot find serial ports anymore.
I have a serialPort parameter with <context>serial-port</context>, but no port is offered from PaperUI.
It seems that bundles related to serial ports are being loaded correctly:

  122|Active     |    1|nrjavaserial (3.14.0)|3.14.0
...
  128|Active     |    1|openHAB Core :: Bundles :: Serial Transport (2.5.0.201904250319)|2.5.0.201904250319
  129|Active     |    1|openHAB Core :: Bundles :: Configuration USB-Serial Discovery (2.5.0.201904250326)|2.5.0.201904250326
  130|Active     |    1|openHAB Core :: Bundles :: Configuration USB-Serial Discovery for Linux using sysfs scanning (2.5.0.201904250327)|2.5.0.201904250327
  131|Active     |    1|openHAB Core :: Bundles :: Configuration Serial (2.5.0.201904250328)|2.5.0.201904250328
  132|Active     |    1|Commons Net (3.3.0)|3.3.0
  133|Active     |    1|openHAB Core :: Bundles :: Serial Transport for RXTX (2.5.0.201904250325)|2.5.0.201904250325
  134|Active     |    1|openHAB Core :: Bundles :: Serial Transport for RFC2217 (2.5.0.201904250325)|2.5.0.201904250325

what could be the cause of missing USB serial ports ?
What else can I check?
(of couse I am sure serial port is visible from Java: if I run code directly linking nrjavaserial it works and my serial port is found correctly).

thanks in advance, Massi