Specific case causes VFB to wipe despite 'Previous Render' set to 'Unchanged'

[Pixelcon]

I have a scene with the setting Previous Render set to Unchanged, but this setting seems to work at random...

In one scene, if I render, save to vfb history, clear vfb, load previous render from history, focus to max, then back to vfb and render, the vfb will wipe before the rendering is started. Very odd.

I have attached another scene I have seems to always clear the vfb if I try to render over a previous render from history...
Please try it.

Render
Save to history
clear vfb
load prev from history
render <- vfb will be wiped immediately before or partway thru rendering.

history.zip

[yavor.rubenov]

Hello,

We only keep the old render if you are rendering a region. If no region is used and you clear the VFB - new renderings will start from scratch.

Best regards,
Yavor

[Pixelcon]

Aha. Thank you