Found it (capacity to conduct foreign relations). But it's not the "problem" criteria for SoP - for SoP the problem criteria is the control of populated territory (e.g. ability of the SoP government to enforce SoP laws there). For example on p10/11 of the source: "has a government...have a legislative body...have a judicary...have an executive, which carries out the laws and has at its disposal a considerable force responsive to its will." - in the case of SoP the territory it claims (regardless of undefined borders) is under Israel occupation/control. All other criteria are more or less satisfied - PLO-EC is SoP provisional government in exile, SoP has established diplomatic relations with many other states, SoP has diplomatic recognition by many other states, SoP accepts the membership obligations and has submitted membership application. The rest of the criteria depend on the judgment of UNSC and UNGA - whether SoP is "peace loving", whether SoP is "able and willing" to carry out the membership obligations. Even if it's deemed "peace loving and willing to carry out the obligations" the "problem" criteria is whether it's "really a state" (because it doesn't have control over populated territory) and the related whether it's "able to carry out the obligations" (because a state needs control over populated territory, otherwise it functions only in the diplomatic realm as a government-in-exile and doesn't have the ability to do anything on the ground). Of course, if the majority of all UNSC permanent members and 2/3rds of the UN members want - for political reasons - they can grant membership to a GiE (turn a blind eye to the lack of territorial control or resort to some reasoning that it's able to comply and only the foreign occupation prevents it, but that occupation is declared illegal by this and that UNSC and ICJ acts, so they won't take it into account, etc.)
Do you insist on adding such OR/SYN unsourced analysis? Unfortunately we don't have the UNSC 2011 report that maybe deals with those issues.