What causes this....

[kmlsoni]

Why 2 cube successfully print and with same support one failed?

[Weliz]

My guess your film on the vat must be loose so when the peeling is done that part dos not stick. Just a guess.

[Archerm]

Or your build plate might need to be re calibrated.

[CADjewelrySchool]

I don't think it is a head calibration issue as the base and supports managed to attached to the build platform.
The supports on the right-side look thinner, than the supports in the middle and right side - so it looks like there was not enough contact on the cube which caused it to fail.

It looks like you are printing @ 42XY, because the projector is further away from the printer @42XY, possibly the brightness from the projector is lower on the left side.
I would suggest that you try increasing your exposure by 0.1sec each print, until you are able to successfully build all 3 x cubes.