I don't have an UM3 and haven't printed with CPE, so the following is from experience with PLA and PET. Usually this sort of defects comes from overextrusion. Or, if it is on the first layer only, it comes from the glass being a bit too close to the nozzle: the advantage is that the layer is squeezed well into the glass, usually with better bonding as result.
I also see brown spots on the print. So I would guess that the blobs come from molten material that is accumulated on the outside of the nozzle while printing (thus due to overextrusion or the nozzle being too close to the glass), and that sags and falls off on the print. The brown is when it starts to get burned.
Usually big light brown chunks and strings come from burned material on the outside of the nozzle, while thin black chips come from the inside, in my experience.
Try printing a small test piece, for example a cube of 15mm x 15mm x 15mm, 100% filled, and see if it still happens after a few layers?
Stay with the printer and watch what happens under the nozzle.
Bad bed adhesion also causes a sort of bobbling, but as far as I experienced, it looks a bit different. If it would be bad bed adhesion, that should clearly be visible from the bottom: there should be indents, like the shape of water drops, but then hollow.
All this is a guess, but it is an educated guess.
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tomulinek 0
Unfortunately i have the same problem with CPE. More solid layers one on the other look overextrused.
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