I've also lost coins with the Mint & Spend function. I tried one coin and 100 coin tried to redeem (spend) over a month ago

Status: 0/unconfirmed
Date: 30/06/17 06:48
Source: Generated
Credit: 100.00 XZC
Net amount: +100.00 XZC
Transaction ID: d1ffec59eac616258a3330f8c174f9ebd1654f262a6bfecc6f5aa81b15320ce2

Status: 0/unconfirmed
Date: 29/06/17 21:11
Source: Generated
Credit: 1.00 XZC
Net amount: +1.00 XZC
Transaction ID: 41cbee413dc6e1b9c928330c6a6c92188a7fcedfe5a1be777b67a64edb4132f2

After that I moved wallet.dat file to another pc. I didn't realize it had no confirmations so lost some more coins on that one. They also show as zero confirmations, but on the first pc there is no trace of them even being redeemed.