You are right that there are conflicting viewpoints about whether or not Vaseline and other types of petroleum jelly, also known as petrolatum, are comedogenic (can cause or worsen acne). There are medical professionals who will say that petroleum jelly will cause acne, while others might argue the opposite. The same also goes for research, though most research points to petroleum jelly being non-comedogenic.
Why might petroleum jelly be comedogenic? Petroleum jelly is very greasy. This greasiness could cause petroleum jelly to be comedogenic. Research has also shown this may be the case, but there is also some more reliable research that suggests that this is false. Because people have wondered if petroleum jelly is comedogenic for a long time, most studies on this topic are a little bit older (pre-2000). Also, most studies that suggest the petroleum jelly might cause acne were done on rabbits, who are much more sensitive to cosmetics than humans are.
A 1972 article that introduced acne cosmetica,1 acne caused by cosmetic products, tested many different cosmetic creams on rabbit ear canals, and found that many of them, including petroleum jelly, were mildly comedogenic. The research also found that using petroleum jelly or other cosmetic substances can cause mild acne breakouts in some woman. This research wasn't extremely convincing that petroleum jelly is comedogenic as rabbits aren't the perfect model for seeing what the effect would be on human skin. Also, the research done on petroleum jelly's effect on actual human skin showed that it caused comedonal reactions, but only in some women.
The most reliable study testing if petroleum jelly is comedogenic is probably a 1996 study by the same man who did the previous study I mentioned.2 The results, after testing different products that use petroleum jelly on different groups of patients, were that there wasn't any comedogenic potential in petroleum jelly. Petroleum jelly also didn't worsen acne at all.
It is most likely that petroleum jelly is not comedogenic. Some studies point to it being comedogenic as a possibility, but rabbit ears are much more sensitive than human skin, so it is impossible to get definitive information from those studies. If you are worried about getting acne from using a product like Vaseline, you should be fine. Odds are, the Vaseline would be helping you more than hurting.
1: "Acne Cosmetica"
2: Petrolalum is not comedogenic in rabbits or humans: A critical reappraisal of the rabbit ear assay and the concept of "acne cosmetica"