I'm trying to embed a very simple Visualforce page inside a standard page layout of custom object.
When the visualforce is run on its own there are no problems.
When it is embedded in the standard page layout I get the message ' Content cannot be displayed: unrecognized Base64 character: *'

The field on the visualforce page is a decrypted field. The field only contains plain text. Any ideas??

Visualforce page:-

<apex:page standardController="Term__c" cache="true" showheader="false" standardstylesheets="true" extensions="ExtVirtualEncryptedTable" > 

<apex:pageblock > 

 <apex:pageblocksection columns="1" title="Tables">
<apex:outputtext value="{!tables}" escape="false" />
</apex:pageblocksection>     

</apex:pageblock> 
     
      
</apex:page>

Extension Controller:-

Public with sharing class ExtVirtualEncryptedTable {

private ApexPages.StandardController controller;

Public string Tables {get;set;}

private final Term__c term;
 
Public  ExtVirtualEncryptedTable(ApexPages.StandardController controller) {
Controller.addFields(new List<String>{'Encryptionkey__c','TableInfo__c','Other_Information__c','Example__c','Unlock_record__c'});


this.controller = controller;
        this.term=(Term__c)controller.getrecord();
        
              
            // Unencrypt data upon loading
           
   if(term.TableInfo__c!=null) {
    Blob cryptoKey = EncodingUtil.Base64Decode(term.Encryptionkey__c);
        Blob string2open2 = EncodingUtil.Base64Decode(term.TableInfo__c);
          Blob decryptedData2 = Crypto.decryptWithManagedIV('AES256', cryptoKey, string2open2);
           Tables = decryptedData2.toString();
           }
           
      }   
    }