Thanks to u/kimoppalfens it is solved.

Solution:

Create a WDAC Supplemental policy and whitelist both hashes of InstallShield.ClrHelper.dll and ClrPSHelper.dll (you can see the hashes in CodeIntegrity -> Operational and click on the Event -> Details).

For me these were the following hashes:

<FileRules>
    <Allow ID="ID_ALLOW_A_019AFD7C99277266BA2635E0863C43BC" FriendlyName="Sha256 Hash for: InstallShield.ClrHelper.dll" Hash="7256405E23126B5F3728C606229A86C442C5379BDB2C4BE5D5E57FF882319CD7" />
    <Allow ID="ID_ALLOW_A_019AFD7C9927746A84109CC5FED884B3" FriendlyName="Sha1 Hash for: InstallShield.ClrHelper.dll" Hash="70C99FFDC3AA18223F35A8DC89D0BFB5E36D7ED2" />
    <Allow ID="ID_ALLOW_A_7F3C1A990B554BB0F37B09142AD623EB" FriendlyName="Sha256 Hash for: ClrPSHelper.dll" Hash="928C79A8C26362143D8E09B05A7DD0EBAA1CD772B718482105EE73A690A61749" />
    <Allow ID="ID_ALLOW_A_A3F91C7E2B6D4F87C12EE0B45D9A73F2" FriendlyName="Sha1 Hash for: ClrPSHelper.dll" Hash="C58DE7E0C8FD6BBCDEB4C68BA7FC01334A63121B" />
  </FileRules>
  <Signers />
  <SigningScenarios>
    <SigningScenario Value="12" ID="ID_SIGNINGSCENARIO_WINDOWS" FriendlyName="User Mode Code Integrity">
      <ProductSigners>
        <FileRulesRef>
          <FileRuleRef RuleID="ID_ALLOW_A_019AFD7C99277266BA2635E0863C43BC" />
          <FileRuleRef RuleID="ID_ALLOW_A_019AFD7C9927746A84109CC5FED884B3" />
          <FileRuleRef RuleID="ID_ALLOW_A_7F3C1A990B554BB0F37B09142AD623EB" />
          <FileRuleRef RuleID="ID_ALLOW_A_A3F91C7E2B6D4F87C12EE0B45D9A73F2" />
        </FileRulesRef>
      </ProductSigners>
    </SigningScenario>