Hi,
Please navigate to your Azure Policy Assignments in the portal using link below:
https://portal.azure.com/#view/Microsoft_Azure_Policy/PolicyMenuBlade/~/Assignments
Once there, check for "Storage accounts should have the specified minimum TLS version". If you have this you could delete the assignment -or- click on the assignment, click edit assignment and on Parameters tab uncheck "Only show parameters that need input or review" and then change effect to Audit (or change minimum to TLS1_2) and save.
Wait a minute or two after deleting/modifying your assignment. You should be able to change your storage account to TLS 1.2 minimum after making above change.
Please click Accept Answer and upvote if the above was helpful.
Thanks.
-TP