Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce RTX 2070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.40
Broken: version: 2.93.0 Beta, branch: master, commit date: 2021-04-15 14:16, hash: rBa4877f9e5408, f903e3a3fd003e5295f7aea35710a77b2e74f846
Worked: (newest version of Blender that worked as expected)
Short description of error
After "Quick Smoke" changing "Flow Type" for already computed frames has no effect.
Exact steps for others to reproduce the error
New Scene, delete cube and add Suzanne (optional probably).
Select object, F3, "smoke" enter on "Quick Smoke".
Press space bar to play the scene, you should see smoke rising around the object.
Press space bar again to stop the sim around say frame 150.
In the Physics Properties, change the Flow Type from Smoke to Smoke+Fire or Fire.
Press space bar to resume the playback.
Observe that new frames not previously computed will reflect the new Flow Type, but when it wraps around to the previously computed frames it only shows the original "Smoke" flow type.
If you save the scene and re-load it, then the currently selected flow type will affect the scene correctly from frame 1.
So when changing "Flow Type" it does not clear frames that have been computed/cached under the previous value.
I looked for some place to explicitly clear that cache without any luck but maybe I just didn't fine it. Since reloading the scene resets the now incorrect frames, it seems to me that changing the Flow Type should immediately invalidate any now-obsolete frames that were computed using the old setting.