There are some rare issues when a client discovers specific product incompatible with User Role Editor Pro. I hope it’s not your case.
Could you give more details about to what plugin do you wish to provide access? May be a hint, which follows below, will be helpful.
How can I give access only to some plugins and not to the rest?
If plugin provides its own user capabilities use theme 1st. If plugin does not provide its own permissions or there is not enough them, use “Admin menu access” add-on with ‘Block not selected’ option:
What theme do you use? What do you try to block/hide? If it’s a commercial product, could you send its copy to firstname.lastname@example.org for the research?