I just imported this list of 40 private keys into Electrum v3.1.0:
("File -> New\Restore -> Import Bitcoin Addresses or Private Keys")
L2KuYHa9hem7ra2Q48FqgiduvXnxmZCAUd5zVr7XeJc1woMkS9oi
L2A953BooZCcsuPRZNXBYdjzkmTjB4hDQmjejxTmQnLWsQU6GGeX
L3VYGYPAb49DRG5epyeZqWdh3vwyMNo6XtMGBFh5HTXs9cXnnX4j
KySmTV889te8v2fSy1dYhD9rcW5DVsrZ1tcrA9drd6uf1hdaTBUX
L5jCAL697W81UimR1xMen4ocbGs5XEhweyWKvsHqcEzStScA49C1
L2mfojT8bycfYupxEL1undKr4e3XVsNR4TGEvqUXoCTBMLB4PYDE
L3EmpvGDgayFqHsWQQ72w4Pqs6pCKfzyHw5ZP5qVZXCaqYCyfeLM
KzXFwdCAVpypA3LWaaxFSEgiNZoqi6iSzTsvy4fi6AYgWtMztUVv
Kx4jQd341Xf1gosKZgAtXwgQ6QqU4QsbDWtJoFBWZFHmNDfj5zW8
KzEixyyh8yGMV6AjFhogKCpcmuBCdUAoy35MsvGahs9SfmhUeoYJ
L4WHLLpPkvSoihsGbaZhYzFMgRxKbBEuAxgGvwgy2r33cnR6XCEX
L1NqoTWNtLZpiLo4KSRQc1wvZy9hGEwWrVX98iMqsXPRTQ3Nd6nw
L2mpb9DJDQiCknfvfCQTjyrMZ2vS8DTn4s1r8QYvVW2d5B67Y9PX
L14K4A5MzQbj2wkPwhYVk2kcM3EZQJPCrvuwTCTgBZCVLLRUQhzh
L4eg4SiTGr4bLFP9qBGd5U9TPF3But79cj7hTTBaktWJGHfJitoK
L5U43DHAjQiaraNpNvqq15SJoytDq9oe9PFdpYdbD4CCBFkH5bHv
Kz9HQcdHnEDw6LkDPwrYnEaer9evxubbrQFpxaX5Ak5GCBv5CDXR
L46B3B4DyKLn5B7K4Z4nqJsY7Vr8jpdSNGJSj7eJoms9YbwA69jf
L4PBsRVFGGF8tR22Ksgb5tocHZgACbXxcLS4XQkiYXD5UjL64xme
L12zBtBT6nADSxbw92uG2d5ub4yx1t6nTPVfy8n92USCCAcJtmbT
L46BVhYNYBpRkxLJiD6gmnKnpP1BcMVL4Zwtzb12JhAYVQtzRero
L47jHgyS4meyC8x4ub7b8e7Qdwek2GMRQm9UYxRmmtmK8Z41aJS1
L2yVbRNypK1kx5CzGZRcBbskUkHkXaLx3TiVz5SfnmdvijSaFSrQ
L4sJgGEUquQz2KFiCoMmNHQuFhcEbjx1SaLmzYtguByfi1tkwrPe
Kz7qhcQVpUeFWh6rPrVadsZMoNEmp9W8nujHTR9E45BXGsMncXoK
L2ccRMcWhxvRVy3ctqm5QRSSTmZAoQn6kavsKwQPHEaB54Vr778X
KxdMvDEbUhMcGuk15KZikzDQwsfoJygHR7T9rLzLeTqK5MHKq5hP
KxCYg3BzorXmzzaXtPHZFXBhgzzJxiy2sFDarDTjJVFfzB5WvgER
L5eVq8bSmFeWYzmcNvHWX9hcUmTTrkBDQYDF2VoVwarzdSFaJs12
KzfveAkG8WhDoxUnfrPFMskxXwTAjnVYNf45t6VESJ4RBikkKoEq
KzRPa9KtDgHNydKCLiE8P9tQZ3J3sj7M7o4Rh34GddHEcGouyx1B
L1zWrArHwo8KUPJaYZtJKktF2XnPjKgcWHezjeveu1BsP3hALoZd
KyLa6ujsCj1NXtXjg2n19CYmz2omaQgmT1cA5CvvivFUYUuu26vT
KyWY9L7avZJ8hE9uEXTh82oE6wjZw5q56ugcXE4Gmg6gaY36B8au
L4xqnQeY4znYLTyspRZmDF4J3d9TeYdSkhjZveRuHJjgycJaScji
L4epffCTTzT5zWo6wYyLFmbHneHzpT31isjPpodfcpHQMcqeqohT
L29YeYT1UKHbqN7Vdyrz6P7jHmvci1ECwaTrSv8xLALL3JCag5L4
L2CkCGGNewLz2Htk9Ni3FqXswTubY6SXcYPqAbgMZYeTcBiTMChb
KyXtRK6XcXs3nMkP9RDkLiajSMeRPntJMwY59kYKBBLUBMFhgXbo
It gave this:
The only time it won't show more than 30 (by default) is if you are using an HD wallet either created from seed or by importing an "xpub" or "xprv". In that instance, you simply need to use the following command on the console: