Running pluginval from both computers could at least give you some idea if something is going wrong on one of them. If for example you have a race condition that is causing an issue, you may find it triggers regularly on one and not the other due to timing differences. There is also a vst3 validator that comes with the vst3 SDK, more info here.
If your plug-in is failing to scan, have you checked it hasn’t been black listed? some hosts will not bother to rescan the plugin unless something like the version number has changed. From memory I believe Logic does this, it also has a special case where it will always rescan if the version number is all zeros. Some hosts may also have a log somewhere which could give you an indication as to what went wrong.
The admin access could be an issue it’s hard to say.