It sounds like you made a typo there. The points you list suggest the regression started between kernels 5.0.1 and 5.1.5:
* The bug does not affect kernel version 5.0.1-050001 (Tested on my install of 19.04 with a manually installed kernel)
* The bug does affect newly build kernel version 5.1.5-050105 (Tested on my install of 19.04 with a manually installed kernel)
Yet your original bug description suggests the bug is in version 5.0.0-15.16-generic too, as does your summary in comment #6. Those conclusions conflict with the above listed findings, so please clarify...
It sounds like you made a typo there. The points you list suggest the regression started between kernels 5.0.1 and 5.1.5:
* The bug does not affect kernel version 5.0.1-050001 (Tested on my install of 19.04 with a manually installed kernel)
* The bug does affect newly build kernel version 5.1.5-050105 (Tested on my install of 19.04 with a manually installed kernel)
Yet your original bug description suggests the bug is in version 5.0.0-15.16-generic too, as does your summary in comment #6. Those conclusions conflict with the above listed findings, so please clarify...