No TV after boot

Hi,
I have installed the following :
Raspberry pi3
Backend frontend Tvheadend 4.2
LibreElec 7.0.2
TV TUNER AVERMEDIA AVERTV VOLAR HD A835 USB
After startup when i try tuning to a dvb T channel, I get the message "http client-no free adapter" in a yellow icon.
I can see the EPG info and the channels but no picture and sound
If I pull out the tuner stick and plug again then everything is ok.
I have tried to put some delay at the prefferences of Tvheadend but didnt work
The thing that I noticed when I open the web interface is that there is no dvb tuner at start up , it appears only after the unplugging
thanks

No use. I looked at the AVerTV DVB-T Volar - MythTV Official Wiki and it is confirmed as a problem of the specific tuner.
Although, it was working without boot problems under osmc for some months