Steps to reproduce:
1. Create a new lwrp project
1. Create an area light
2. Position it near static geometry
3. Bake lighting
4. Notice that the area light does not contribute to the baked lighting

Expected result: Area light hidden "Mode" parameter should be always set to "Baked"

Workaround:
1. Change the light type to Point
2. Change mode from Realtime to Baked
3. Change the light type to Area
4. Bake lighting and observe that the light is baked now

Reproduced in: 2019.3.0a11, 2019.1.3f1, 2019.1.0b1
Not reproduced in: 2018.4.1f1
Packages reproduced in: 6.9.1, 6.5.3, 5.7.2, 5.2.3
Packages with no repro: 4.1.0