Many.

1. Forged land title deed.

2. Locals don't like you.

3. Barrangy doesn't like you. Fits above.

4. Combination of 1+2+3.

5. As a foreigner you don't have legal rights, so you must either buy via a corporation or through a spouse EXCEPT if it's a condo that is 50%+ owned by Filipinos OR a specially crafted foreign owned corporation.

6. Anti Dummy Law is big - and can mean instant voiding of corporate veil and instant liability. Philippine courts are self interest and will always put local over foreigner everyday UNLESS in cases of free trade zones or speciality corporations granted by Philippines SEC.

7. Marriage - usually fall out between husband and wife. Whomever is the Filipino has all the assets in their name. While technically you can set it up so that the Business license is only in the filipinos name, and you can have all liquidity/wealth in yours, especially in an untouchable nature -e.g. foreign bank via Citi/HSBC/Bank of China any local land claims can be instantly grabbed by the filipino national.

8. Land leases are actually more secure, and cheaper because you turn an capex into an Opex. Most filipinos will welcome the monthly revenue stream, and then probably argue 5-10yrs down the road when they want more, but depending on the family structure / background these sort of agreements are usually kept because of trust/rapport, but you need to wine/dine and take care of the relationship. It isn't as traditional as "check is in the mail" in western countries.

9. The legal system is very slow, on purpose and depends on WHOM you know. You need to really break into the area, make friends and create bonds - not only will the friends you make help you avoid legal obstacles, they will know someone who can help you. That is key - knowing whom to know. That is how Filipino Culture works. You can not just go in there/browse property online/grab a quick title and go. There is little to no actual title underwriting, the government is at a standstill with its title office and working and can not verify titles and it is a common scam. You can go see lots in person and they have signs saying "DO NOT TRUST PERSON NAMED: ADAM LA CRUZ" with his picture or "LOT NOT FOR SALE" while you can go online and see listings of brokers who say it is and who'd happily take your money.

Outside NCR/Manila - land is cheaper, easier to purchase if you make friends with WHOM lives there. Everyone in the PH loves to meet new people and feel proud that you want to invest in the area - but you actually need to put your feet on the ground, go to the the area where the land is, ask to see the barrangay cabesa (neighborhood captain) and then meet their family, judge from their socioeconomic background if they're trustworthy e.g. are their kids in "GOOD" schools not just a nice house or a car or two / wealthy vs debt trapped - and build rapport.

Rotary club can be a good place to start. As well as church groups and other volunteer places.

THAT is the only way you can successfully get land in the PH - if you're displacing farmers, you may get shot. There are also tons of shoreline land scams involving the New Philippine Army (kinda liberal guerilla group similar to FARC but, nicer) that common money raising method is to forge deeds, demand cash purchase, and then intimidation - this is common for resorts.

tl;dr You gotta go where you're buying the land, talk the talk, walk the walk, wine and dine and make sure you have good friends who went to the top unis in the country and are in law. DLSU, UP, Aeteno should provide good network groups.