Mediawiki is case sensitive, except for the first letter of the first word, which is autocapitalized during article creation. This ended up being problematic in cases where other parts of a multiword title were capitalized. Current policy is not to capitalize words in links / titles unless they're an abbreviation, the first character in the string, or a proper noun. If there is some confusion, try to leave a redirect.
[[Fly Fly Hobby]]
[[Model Planes]] (delete and fix) [[Grand wing systems]] (delete and fix) [[multiplex easy star]] (delete and fix)