Lines fail to stay down, get dragged by the nozzle, or the part pops off within the first few layers.
print not stickingcomes loose immediatelynozzle drags plastic around
Ordered by how often each is actually responsible, not by how interesting it is. Work down the list.
Lower the Z-offset until the lines flatten slightly and fuse into a solid sheet with no gaps between them.
Wash the sheet with dish soap and warm water. Isopropyl alone redistributes finger oils rather than removing them — this surprises people who have been "cleaning" with alcohol for months.
Tram the bed hot with mesh disabled, then re-run the mesh. Adhesion that varies by location is always tram, never temperature.
Raise the bed to the material starting temperature. Check with an IR thermometer if you suspect the readout — bed sensors drift.
Drop first-layer speed to around 20 mm/s. Plastic needs contact time to bond.
Block the draught or enclose the printer. This one is invisible and gets misdiagnosed for weeks.