TemplateNotFoundException for index.ftl while customizing account theme in RHBK

Issue

• In process of migrating RH-SSO 7.6 to RHBK 22. In process of migrating from RH-SSO 7.6 to RHBK22 we have tried to enable our own custom account theme in RHBK. With base as the parent theme in our custom theme we are facing below error when accessing the account management console :

ERROR [org.keycloak.services.error.KeycloakErrorHandler] (executor-thread-9) Uncaught server error: org.keycloak.theme.FreeMarkerException: Failed to process template index.ftl
        at org.keycloak.theme.freemarker.DefaultFreeMarkerProvider.processTemplate(DefaultFreeMarkerProvider.java:52)
        at org.keycloak.services.resources.account.AccountConsole.getMainPage(AccountConsole.java:151)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
.......
Caused by: freemarker.template.TemplateNotFoundException: Template not found for name "index.ftl".
The name was interpreted by this TemplateLoader: org.keycloak.theme.freemarker.DefaultFreeMarkerProvider$ThemeTemplateLoader@553eb1b7.
        at freemarker.template.Configuration.getTemplate(Configuration.java:2957)
        at freemarker.template.Configuration.getTemplate(Configuration.java:2777)
        at org.keycloak.theme.freemarker.DefaultFreeMarkerProvider.getTemplate(DefaultFreeMarkerProvider.java:66)
        at org.keycloak.theme.freemarker.DefaultFreeMarkerProvider.processTemplate(DefaultFreeMarkerProvider.java:45)
        ... 44 more

• Facing Template not found for name "index.ftl" while creating custom theme in RHBK