I’m assuming each author is listed on a separate line in the Author field of the Endnote record. I’m running Endnote 7.7 with Windows 10 and the three initials appear capitalized so unclear if this may be a Mac-related issue. Suggest you contact tech support in the interim try using the “Change Case” feature to see if this helps to retain the capitalization of H. A. L. (Go to the Endnote toolbar and select Edit >Preferences >Change Case.)
It’s an option under the output styles to use A. B., A.B. A B, or AB. I don’t think that’s the problem. The library has 100s of entries and all display fine except for the one with three middle initials …
That is fine, but you need to separate them in the record itself. Each should be separated by a space or endnote thinks that they are a word. At least try it?