Reproduction steps:
1. Create a new HDRP template project
2. Create a new Area Light and change its Shape to Tube/Rectangle
3. Make sure you can see the Light on the wall
4. Adjust the Length/Size so Light becomes visible outside of its range indicator
5. Adjust the Camera so the Light's range indicator is outside FOV

Expected result: you will still see the Light
Actual result: the Light becomes invisible

Reproducible with: HDRP 4.10.0 (2018.4.13f1), HDRP 6.9.2 (2019.2.14f1), HDRP 7.1.5 (2019.3.0b12), 7.1.6 (2020.1.0a15)