This happens in conquest too on just about all difficulties. Starter cruises with no hits against, tires, you put in any reliever and the AI will homer shortly.
The way I “fixed” it vs the AI is bring in another starter and throw 2 blatant balls to first batter faced. You can also use your tiring starter to get the AI batter to 2 strikes and bring in anyone, get the K and you are 99% safe from the obligatory AI homer off new pitcher.