The used Ubuntu version (16.04) is obsolete, also mesa was updated (from 11.2.0 as per report to 18.0.5-0ubuntu0~16.04.1 in 2018), can you check if the problem is still reproducible with the newer mesa or on a newer Ubuntu?
The used Ubuntu version (16.04) is obsolete, also mesa was updated (from 11.2.0 as per report to 18.0.5- 0ubuntu0~ 16.04.1 in 2018), can you check if the problem is still reproducible with the newer mesa or on a newer Ubuntu?