One work-around I found was having adding these components to another project, then when I opened Delphi 10.1 Berlin I opened this project and then closed it before opening the project that had problems with the components, and it all worked fine.
In the end the solution I found was the following:
- In the package itself, find the unit with the 'Register' procedure.
- Check 'DesignInf' is in the uses clause.
- At the top of the 'Register' procedure add 'ForceDemandLoadState(dlDisable);'
- Install the package again.
What this does is disables the IDE from using the smart loading of installed packages, this means when the IDE starts it always loads the installed packages.