Not sure which plugin(s) you're referring too, I could guess you mean the Frequency Manager + Scanner plugin found at sdrsharpplugins.com (in spite of website name, it's home only to that one plugin) - v1.31 was released and then v1.4 came after it with some bug fixes and additions to make it even better. Either one will work with the most current version of SDR# which is v126.96.36.1994 (the dev version) without issues that I'm aware of. Great plugin as well, I have a few thousand frequencies stored nowadays with a lot of info for each one as well.
And of course it goes without saying that if you're serious about SDR# you should definitely check out the Yahoo Group for that program at https://uk.groups.yahoo.com/neo/groups/SDRSharp/info as there will be plugins announced and released from there as well (that can't be found on that list yet).
I recommend you read the Installation section of the User Guide.
If you don't do so, at least follow these instructions:
Unzip the freqmanager.zip file to a convenient folder.
* DO NOT unzip it to the SDR# folder for this will cause the plugin
installation to fail.
Please run program PluginsSetup.exe to install the plugins.
* DO NOT install the documentation to the SDR# folder.
If the installer has no Next, Back, or Cancel buttons displayed, this is
often because the screen's DPI (screen dots per inch) is set higher
than 100%. Temporarily reduce the DPI to 100% and run