drowt, we understand that maintenance works can be an inconvenience: no-one wants to wait to make a transaction. However, please understand that we wouldn't start the maintenance if it were possible to perform certain procedures without affecting our users. Blockchain is a volatile environment, and we're updating our wallets regularly to make sure our users stay safe.
By the way, the maintenance on the ZCash wallet was completed, you can retry your transaction, there shouldn't be any issues with it. Sorry for taking so long!