Anyway such issue can be pretty cruel: the transaction just disappeared (no inputs and no outputs in the wallet while the tx is unspent) from the wallet while everything else worked perfectly fine so it could be easy to simply lose it in my own wallet.
your welcome.
that is the issue with using an SPV wallet. you are trusting a third party to give you the transactions that belong to you. that third party can be malicious or simply slower or on an orphaned chain or lots of other things and give you bad information.
the good news is that it can not give you transactions that doesn't belong to you since you have the block headers and you receive the full tx and it has to be correctly signed.
but it can withhold transactions that belong to you and you will have no way of knowing it with just having the block headers.
https://en.bitcoin.it/wiki/Thin_Client_Security
https://gist.github.com/justusranvier/451616fa4697b5f25f60