1) My GTX 1070 does not recieve WUs on my Ryzen 1700x with Lubuntu 18.04: STILL DOES NOT DOWNLOAD WUs.
2) Second try. The app_config works on the GTX970.

The fix is to run 2 or more tasks per GPU. My tests have shown that the following app_config.xml

<app_config>
   <app>
      <name>amicable_2_64</name>
      <max_concurrent>3</max_concurrent>
      <report_results_immediately/>
      <fraction_done_exact/>
      <gpu_versions>
          <gpu_usage>0.5</gpu_usage>
          <cpu_usage>1</cpu_usage>
      </gpu_versions>
    </app>
</app_config>

is enough to get 100% load on GTX 1080 Ti now, but I'll have to switch to 4 tasks per GPU soon.

I do have two questions:
1) My GTX 1070 does not recieve WUs on my Ryzen 1700x with Lubuntu 18.10. What is wrong?
2) On my other system with 2 GTX970 under Windows 7, the above App_Config does not work. Does not run two Wus at the same time: I changed <name>amicable_2_64</name> to <name>amicable_10_20</name>.
I should say that I run App_Config files on other projects with no problems.

Has anybody any suggestions?

Thanks

The fix is to run 2 or more tasks per GPU. My tests have shown that the following app_config.xml

<app_config>
   <app>
      <name>amicable_2_64</name>
      <max_concurrent>3</max_concurrent>
      <report_results_immediately/>
      <fraction_done_exact/>
      <gpu_versions>
          <gpu_usage>0.5</gpu_usage>
          <cpu_usage>1</cpu_usage>
      </gpu_versions>
    </app>
</app_config>

is enough to get 100% load on GTX 1080 Ti now, but I'll have to switch to 4 tasks per GPU soon.