Furthermore, when I click the refresh button multiple times, Ledger app sometimes loads the unconfiremed transactions, sometimes it does not?!
Do not worry, i had the same issue a few days before with my ledger when i tried to send some bitcoins.
That is normal if the network is currenty congested, and sometimes ledger has some issues on their platforms.
If you do not like how it is going or if you are feeling unsafe about it, you can export your private key by just getting it from the software (the manager)
Or just use your 24 words and export it to a Digibyte friendly wallet, they are not lost, they are just in the blockchain, only that you probably sent it with a low fee.