Nope! There will be no problem if you drop a year after your 12th regarding the admission. Now if you are applying for some entrances then you must know that there are some limits. For example, in JEE ADVANCED you can only give two attempts. The first one is on the year of the 12th and the 2nd one is on the next year. So you must check such criterions. Otherwise there are no such problems regarding the admission.

To know more about the career after 12th visit the link below:

https://school.careers360.com/articles/courses-after-12th

I hope this answer helps. All the very best for your future endeavors!