Palo Alto Prisma Cloud - High severity alert opened for several days

Original query, unchanged.

let ResolvedAlerts = PaloAltoPrismaCloud
| summarize result = make_set(Status) by AlertId
| where result has 'resolved'
| project AlertId;
PaloAltoPrismaCloud
| where Reason =~ 'NEW_ALERT'
| where AlertSeverity =~ 'high' 
| where Status =~ 'open'
| where AlertId !in (ResolvedAlerts)
| extend alert_time = now() - TimeGenerated
| where alert_time > 1d
| extend ['Opened Days'] = strcat('Alert opened for ', strcat(toint(alert_time / 1d), ' days'))
| distinct AlertId, AlertMessage, AlertSeverity, ['Opened Days'], ResourceId, UserName
| extend AccountCustomEntity = UserName