Error: Activation of solutions with sandboxed code has been disabled

Hi all! I am getting a weird error for my company’s main SharePoint site collection in our Office 365 tenant, I am getting a weird error when trying to create a new subsite using an OOTB template (classic team site): Activation of solutions with sandboxed code has been disabled. The reason I say weird is because There isn’t any sandbox code that we deployed and although we do have items from the SP Store I have gotten rid of most of them and still the same issue. I am able to create subsites in other site collections and am able to create other site collections using OOTB templates. 

I even ran the Powershell from Github designed to give a report on sandbox solutions in your SP site (https://github.com/OfficeDev/PnPTools/tree/master/Scripts/SharePoint.Sandbox.ListSolutionsFromTenant) to see what the sandbox solutions are in our main site and the report was blank indicating that there are no sandbox solutions in that site so there is something else going on here throwing the sandbox error but not because we have any sandbox solutions. Now, I admit that I may need to run the script on every subsite in that main site collection and plan to do so tomorrow (teaching class today).

I am reaching out to see if anyone else has experienced something similar and, if so, have you found a solution. Looking forward to the responses!