Hello,
I am trying to display a message to the user based on the values selected in a record's picklist field. The following code works correctly for single values, until multiple values are selected in the picklist. When multiple selections are made, the code is not displaying the desired message see bolded code snippet below:

<apex:page standardController="Account"
           sidebar="false"
           showHeader="false"
           showChat="false">

<apex:pageMessage title="Client Treatment Alert"
                  summary="This client has had prior Technology Issues." 
                  severity="info" 
                  strength="3"
                  rendered="{!Account.Client_Treatment__c = 'Prior Technology Issues'}" />
                  
<apex:pageMessage title="Client Treatment Alert"
                  summary="This client is Detail Oriented." 
                  severity="info" 
                  strength="3"
                  rendered="{!Account.Client_Treatment__c = 'Detail Oriented'}" />
                  
<apex:pageMessage title="Client Treatment Alert"
                  summary="This client is Price Sensitive." 
                  severity="info" 
                  strength="3"
                  rendered="{!Account.Client_Treatment__c = 'Price Sensitive'}" />

<apex:pageMessage title="Client Treatment Alert"
                  summary="This client has experienced Multiple Transitions." 
                  severity="info" 
                  strength="3"
                  rendered="{!Account.Client_Treatment__c = 'Multiple Transitions'}" />                  
 
<apex:pageMessage title="Client Treatment Alert"
                  summary="This client had prior Service Issues." 
                  severity="error" 
                  strength="3"
                  rendered="{!Account.Client_Treatment__c = 'Prior Service Issue'}" />                                                                   

<apex:pageMessage title="Client Treatment Alert"
                  summary="This client had Prior Return Accuracy Issues." 
                  severity="error" 
                  strength="3"
                  rendered="{!Account.Client_Treatment__c = 'Prior Return Accuracy Issues'}" />                  
  

<apex:pageMessage title="Client Treatment Alert"
                  summary="This client has multiple Client Treatment Alerts. Please reference the Client Treatment field for more details." 
                  severity="error" 
                  strength="3"
                  rendered="{!Account.Client_Treatment__c != 'Prior Return Accuracy Issues; Prior Service Issue'}" />   
</apex:page>

Any thoughts on how I can incorporate multiple selected values scenarios into this design? I have tried changing the semi-colon to a comma, but that also didn't work. I feel like I have exhausted my research options. I would appreciate any feedback!

Thanks,
Mitch