Steps to repro:

1. Open attached project and 'ProgressiveLightmappingExample' scene;
2. Clean GICache and Baked Lighting data;
3. In the Lighting window press 'Generate Lighting' button.

Expected result:
Bake proceeds without errors.

Actual result:
Errors are shown:
'Progressive Lightmapper: Initialize lightmap data job skipped - out of memory'. See the attached video and Editor.log.
Regression introduced in Unity 2019.2.0.

Notes:
- The issue might not happen consistently: if it doesn't happen, try following: clean GI cache and baked data in the current project, re-download the project to another location on the disk, open the newly downloaded project in the new location and follow the repro steps again;
- Reproducible in 2019.2.0a6;
- Not reproducible in 2019.1.0b5, 2018.3.7f1;
- Reproducible only on OSX 10.14.3; not reproducible on Windows 10.
- The issue doesn't stall the bake, however, it slows it down to the great extent.