Update Remove/Heal tool (LR Classic 13.3) fails to work properly on a masked area

So I have files where a remove/Heal element occurs on top of a masked area. In version 13.2 the thing removed/healed properly disappeared in areas affected by masks - eg. reducing the exposure. 

In this example, a dark mark on the background is removed by the Heal tool but when the background is made darker using a "Background" mask with exposure reduced, it removes the mark but also introduces a light area in its place which can't easily be removed by other masks. The same problem occurs with the Remove tool. 

Photo 1 - neither tool and no background adjustment
Photo 2 - Heal tool and no background adjustment
Photo 3 - Background adjustment only
Photo 4 - Heal tool and backgadjustment

So now I can't work on files I originally retouched using 13.2 because healed/removed blemishes suddenly exhibit this problem. 

Looking forward to 13.4 ASAP

Cheers

Stefano

LR Classic 13.3
Windows 10 (22H2)