This is the TermoFisher answer in their FAQ section:
I have mistakenly frozen my lipid reagent—can I still use it?
Freezing can alter the integrity and composition of the lipid particles. The performance of the reagent may be affected, and it may only work for the first week or so. It is safer to purchase a new vial to ensure function.
In general, lipid particles should not be frozen as the freezing process could alter the 3 D structure leading to a change in size distribution and loss of internal contents. Depending on the application, changes in particle size can have a dramatic effect on functionality.