I just made an observation: With 1.75 I have to hold SHIFT down before clicking on the Oolite icon in order to clear the cache. Previously I used to click first and then press and hold SHIFT.
When you do a lot editing with plists, it is easier to always reset the cache.
On the mac, open the preference folder of your library and look for the file "org.aegidian.oolite.plist".
It is no text file on the mac, so you must open it with the plist editor to read and edit it. Add an entry with a boolean: "always-flush-cache" set to true.
Than you never have to worry again. And building the cache on every startup, probably takes less than a few seconds extra on startup. Much less that the time you loose when forgetting to press the key when needed.