Windows 10, vim 9.0 E492: Not an editor command: MarkdownPreview

**Describe the bug**
After installing markdown-preview.nvim with VUNDLE the plugin is working. But with each restart of vim I get **Error 492: not an editor command**.
If I reinstall the Plugin, it works again until I close vim.
Looks like my installation does miss some path setting ...

I am facing this since vim 8.2, now after upgrading to vim 9.0 it keeps the wrong behavier.

Inside my .vimrc file I do have inside the vundle Plugins section:
`Plugin 'iamcco/markdown-preview.nvim'`

and this is working, as I always can activate the plugin with _:PluginInstall_.

**Expected behavior**
After installing Vim should know the Plugin on every start.

**Desktop (please complete the following information):**
- OS: Win 10, 64bit
- vim: 9.0 (and before vim 8.2), with VUNDLE

Install steps do not work:
- `source %` -> E499: empty file name for '%' or '#', only works with ":p:h"
- `:PluginInstall` -> works without error
- `:call mkdp#utils#install()` -> E117: Unknown function: mkdp#utils#install
- But the `:MarkdownPreview` works (after PluginInstall)

Log:
I generated a log using _vim -V9myVim.log_
Inside this logfile I do not see any comment on your plugin.
If I search "markdown" inside the log, nothing is found.

Could it be that something is missing and there for the plugin is not called at all during startup?
Regards,
PifPof