Hello,
With the security patch 3.7.3 I had to change the way balances are calculated so that any unaccepted or pending withdrawals are subtracted from user balances. If they are cancelled they stop being subtracted. This was due to reports that the plugin, once used together with the Exchange extension, could be used to steal funds. Now that this is fixed, I also provided a way for old pending/unaccepted transactions to be cancelled in 3.7.4, so that negative balances are not caused by this. The cron job by default cancels any transactions that have not been accepted within 24 hours. If this is the reason your users see negative balances, this will be resolved at a maximum of 24 hours after installing 3.7.4, or you can speed this up by changing the setting “Wallets” -> “Cron Settings” -> “Cancel old unconfirmed/pending transactions”.
I cannot think of another reason why users would encounter this problem. I would have to see some data for an example user (i.e. the transactions for one user and coin). A question: Are you using the Exchange extension?
thanks