Monad Transformer and applicative Maybe

Inside a do block of a ExceptT String IO ()

I have a function that produces a ReaderT like so:

type UDCEnv = (AWS.Env, Bool)

uploadVersionFilesToCaches :: S3.BucketName
                               -> FilePath
                               -> [GitRepoNameAndVersion]
                               -> ReaderT UDCEnv IO ()

I just so happen to have a Maybe FilePath so I create my ReaderT like so:

let maybeReader ::  Maybe (ReaderT UDCEnv IO ()) =
    uploadVersionFilesToCaches s3BucketName <$> maybeFilePath <*> Just gitRepoNamesAndVersions

I can even run the ReaderT like so:

let maybeIO :: Maybe (IO ()) = 
    runReaderT <$> maybeReader <*> Just (env, shouldIgnoreLocalCache, verbose)

Everything works fine as long as I use let expressions. As soon as I drop the let in the expression above to actually try to have expression evaluated Applicative gets types as ExceptT String IO FilePath instead of Maybe

Couldn't match type ‘IO ()’ with ‘()’
Expected type: ReaderT UDCEnv IO () -> UDCEnv -> ()
  Actual type: ReaderT UDCEnv IO () -> UDCEnv -> IO ()
In the first argument of ‘(<$>)’, namely ‘runReaderT’
In the first argument of ‘(<*>)’, namely
  ‘runReaderT
   <$>
     (uploadVersionFilesToCaches s3BucketName <$> maybeFilePath
      <*> Just gitRepoNamesAndVersions)’
/Users/blender/Code/Personal/Haskell/Rome-Public/src/Lib.hs: 82, 73

Couldn't match type ‘Maybe’ with ‘ExceptT String IO’
    Expected type: ExceptT String IO FilePath
      Actual type: Maybe FilePath
    In the second argument of ‘(<$>)’, namely ‘maybeFilePath’
    In the first argument of ‘(<*>)’, namely
      ‘uploadVersionFilesToCaches s3BucketName <$> maybeFilePath’

I think the first error is because I'm missing some liftIO somewhere.

However I have no idea what to do about the misunderstood Applicative.

I could case analysis on the Maybe of course instead of using Applicative but I would really prefer not to.