Iron Golems cannot spawn directly in nether portals even though they are transparent blocks. As you can see from the screenshot, the iron golem will spawn under the platform instead of in the nether portal half of the time. I say half of the time because they can actually spawn on the north west corner of the non-obsidian block (deepslate brick in my case) and will get transported to the nether. But the times that the spawn tries to occur on the northwest corner of the obsidian block with the nether portal directly on it, the iron golem will spawn below the platform. I believe that this is a bug because Iron Golems are able to spawn in other transparent blocks such as water and even lava. Fixing this will allow iron golem farms to be able to capture every single spawn spot possible, instantly remove iron golems from the cap, and only use 10 villagers which will be a tremendous upgrade for Bedrock Edition and satisfy iron farm enthusiasts such as myself.