Tvheadend

Hello there,

i'm using a Digital Device Max S8 with tvheadend 4.2.8.36 which is working fine.
I'm using a unicable setup with fmode=3 also.
The card and the system is working fine, all 8 tuners are working and i can record with them.
But there is one catch:

After a reboot or a restart of the tvheaded server the first tune of a channel is not working.
How to fix this manually:
I can wait roughly 10 seconds and tune in again, or change directly to the next channel, then everything is working
as expected. All 8 tuners than work.

This is the short version of the wbif debug log:

2020-02-21 15:38:33.664 mpegts: 11493.75H in DVB-S Network - tuning on MXL5XX #7 : DVB-S #0
2020-02-21 15:38:33.906 subscription: 0001: "127.0.0.1 [ user | Kodi Media Center ]" subscribing on channel "Das Erste HD", weight: 100, adapter: "MXL5XX #7 : DVB-S #0", network: "DVB-S Network", mux: "11493.75H", provider: "ARD", service: "Das Erste HD", profile="htsp", hostname="127.0.0.1", username="user", client="Kodi Media Center" 
2020-02-21 15:38:34.012 mpegts: 11362H in DVB-S Network - tuning on MXL5XX #6 : DVB-S #0
2020-02-21 15:38:34.256 subscription: 0002: "127.0.0.1 [ user | Kodi Media Center ]" subscribing on channel "ZDF HD", weight: 40, adapter: "MXL5XX #6 : DVB-S #0", network: "DVB-S Network", mux: "11362H", provider: "ZDFvision", service: "ZDF HD", profile="htsp", hostname="127.0.0.1", username="user", client="Kodi Media Center" 
2020-02-21 15:38:44.228 subscription: 0001: service instance is bad, reason: No input detected
2020-02-21 15:38:44.229 subscription: 0002: service instance is bad, reason: No input detected
2020-02-21 15:38:46.229 subscription: 0001: No input source available for subscription "127.0.0.1 [ user | Kodi Media Center ]" to channel "Das Erste HD" 
2020-02-21 15:38:46.229 subscription: 0002: No input source available for subscription "127.0.0.1 [ user | Kodi Media Center ]" to channel "ZDF HD" 
2020-02-21 15:38:46.924 subscription: 0002: "127.0.0.1 [ user | Kodi Media Center ]" unsubscribing from "ZDF HD", hostname="127.0.0.1", username="user", client="Kodi Media Center" 
2020-02-21 15:38:46.924 subscription: 0001: No input source available for subscription "127.0.0.1 [ user | Kodi Media Center ]" to channel "Das Erste HD" 
2020-02-21 15:38:48.925 subscription: 0001: No input source available for subscription "127.0.0.1 [ user | Kodi Media Center ]" to channel "Das Erste HD" 

So i tried to generate a debug log of tvheadend, but as i don't know where to look exactly, i did a log all, but 1,2 Gig are a lot to read and search for.

I have two questions:
1. What would be the best bet to log in the debug log to find the problem?
2. Maybe there is a option which i should try to change to get the card working on the first tune of a channel.

If you need any more info then go ahead, i try to answer as soon as possible.