Custom plugin does not show update notification

Same Question with this blog:https://intellij-support.jetbrains.com/hc/en-us/community/posts/360000717919-Custom-plugin-does-not-show-update-notification?page=1#community_comment_13942805785106

BackGround

I developed a custom plugin and deployed it to an enterprise plugin repository and put the “updatePlugins.xml”.

The plugin is then read from that xml and can be installed.

I checked that I want to receive an update notification/sticky balloon for plugins in the IDEA settings page.

I checked that I choose check update for plugins in the IDEA settings page.

I rewrite the LAST_TIME_CHECKED field's value to 0  in the update.xml  which is in the IDEA local  config folders. 

Question

Problem1:  when I manually go to Help->Check for Updates , The IDEA doesnt show a notification that info me there is a update,through I choose I want to check update for plugins in the settings

but  when I manually have a look at the plugin list, I can see a blue button with the label "Update".

Problem2: through I rewrite the LAST_TIME_CHECKED，but it still not work,when I rewrite the settings and restart ,it still not info.

So why is it that IDEA knows about the update, but does not show a notification/balloon?

Is it because of an enterprise repository, or my settings is incorrect or My IDEA has bug or other?

Please help here, since it is very annoying to inform all plugin users that they should manually check for updates.