I can't think of too many situations where a 60km "OTH" amphibious assault would be needed by the PLAN, tbh, even in a Taiwan scenario. Certainly not within the next decade or so.
A 60km distance from shore isn't really that far at all, and for all the hype of calling it "over the horizon," it is still uncomfortably close to a foe with any kind of modern, functioning shore based AShM apparatus. Not to mention the LCAC design at present is quite limited in its payload, and that the PLAN are also investing in the far superior Zubr that are also capable of Taiwan operations or even those within the first island chain... all that makes the need for an OTH amphibious assault capability revolving around LPD deployable LCACs seem low in priority.
So in other words, I suspect the reason the PLAN hasn't tried to pursue many LCACs is because they don't feel the capability is relevant to their needs, or at least not when there are other more relevant and pressing needs.
To elaborate, I think a big limitation at present is that the PLAN doesn't have anywhere near the number of ships where it makes mass producing LCACs a viable proposition. The USN has over 70 LCACs, with 8 Whibdey Island LSDs (each able to carry 4 LCACs), 9 San Antonio LPDs (2 LCACs each), and 8 Wasp LHDs (3 LCACs each) along with a few other LSD and LHA classes. That adds up to a massive fleet of distributed LCAC number, and a very high surge/first wave volume. And of course, to conduct an amphibious assault you also need sea control, meaning a capable regular navy.
For the PLAN, I imagine it would make little sense to invest in a large number of LCACs when they only have a limited number of LCAC carrying vessels, and when they are probably unable to reliably assert sea control in their areas of interest. But what does that say about the 071 class and its massive well deck? It just says to me that they decided to future proof their LPD class, with the intention that that eventually, within 071's service life, they would have the ability to conduct sea control, and have enough distributed LCAC carrying vessels, where mass producing LCACs would be a sensible decision.
But until that day arrives, it makes more sense to use 071s either in the ultra far from shore, high intensity role as an air assault/helicopter carrying LPD against a well defended environment, or a very close to shore, very low intensity role as an AAV carrier where it drops off a large number of AAVs in a relatively pacified environment.