encryption information packets

[aamert7]

hello, i am establishing a connection between my phone android and nrf5 DK using nrf connect app , and trying to capture LTK , using btlejack on a single micro-bit chip,
many attempts i failed to capture all the packets and the connection always lost so fast, the best was attempt when i could capture the following packets together :

• pairing request
• pairing response
• pairing public keys.
• pairing random keys.
• DHkeys checks.
• LL_ENC_REQ
• LL_ENC_RSP
  but nothing about encryption information that i could discover the LTK by them,
• i tried to use crack, it failed ( not able to crack due to following error: LE secure connection)
  any suggestions guys how to fix this issue, or if i am able to derive the LTK from the packets i captured or they are useless.