Just wanted to ask if anyone else notices a serious lack of Rubber, Tropical wood, Oil, and Silk during the later part of the game. Especially the rubber since it makes producing electric gear very difficult. Is there any solution to it?
Just as in real life, some resources are always in short supply. In this case it's coal during the early-mid game for most nations and rubber in the late game. Oil isn't abundant either but you can manufacture synthetic oil from coal so it's not as big of a problem late game. Tropical Wood is very problematic indeed in the late game as most of it becomes rubber, leaving very little actual tropical wood left in the world. The good thing is that only luxury furniture requires tropical wood so with all the RGO output bonuses and factory input bonuses it shouldn't be too big of a problem unless you spammed luxury furniture factories all over the place in which case they'll simply go broke unless you constantly subsidize them. Silk is abundant throughout the game, never had it been a problem. The most I can think of is that you're cut out from silk supply since the UK holds most of the silk in the world(in India) so when you're at war with the UK they stop selling you silk.
As for what you can do about it, you can conquer territories with these resources to corner the market. In the early game you must secure yourself a good amount of coal to get your industry going, if you're playing a great power than you will generally have enough coal to get going, if not than you'll need to conquer some coal provinces fast. Considering that China and Korea are producing most of the world's coal than that's obviously the go-to place to get coal, Korea is easily annexed at once for max 10 infamy once you research Nationalism and Imperialism, Manchuria is a puppet of China so you have to fight China and all its puppets, but it's still not that hard. If you don't want to go after China(because it's generally considered as a cheesy strategy) than there are alternatives like Madagascar, the Boer states, etc, and of course taking lands from European countries as Europe has quite a bit of oil. For oil it's generally best to just sphere the main oil producers which are Venezuela and the Arabic states. There's also oil in Indochina, most notably in Brunei and the Dutch colonies there so those are good to have as well. Rubber is located throughout central Africa as well as Indochina(Siam, Dai Nam, Cambodia, Burma, Johore and the Dutch colonies mostly) so those are all places you should prioritize your conquests in. The other major rubber producer in the world is Brazil, which is extremely expensive to conquer so it's best to just sphere them and make sure they don't reach GP status(removing them from your or anyone else's sphere). Tropical Wood is in the same places mentioned above for rubber, as most tropical wood provinces convert to rubber but some don't so those remain as tropical wood. Note that there are some other places I didn't mention like oil in Texas and the Caucasus, rubber in a single province in Russia, some tropical wood in Sweden, etc, because these places are generally not worth the trouble due to who's holding them and their locations. Still if you want to go after them it's fine, just not worth as much as the unciv territories and colonies which are much easier to take and generally provide more resources.
Note that even if you corner the majority of the market the supply of these resources is still very limited. So don't overbuild factories that rely on these resources. All the late game industries are great, but keep the factories at reasonable levels(so don't get level 20 Automobile/Tank factories for example as you'll never be able to support them). Even in the late game, the vast majority of your industry should be using resources that are plentiful such as liquor, coal, fabric, timber, etc. The late game factories and others that use rare resources like Luxury Furniture should be built obviously but only in small numbers so that your demand doesn't exceed your supply.