What happens if fixed or floating charge becomes invalid?

1-

Charge becomes invalid if:

Floating charge: 12 months period
Fixed charge: 6 months period
…of commencement of liquidation period.

(note: this part is clear, but 2 part is not clear)

2-

What I cant able to understand what does that mean by
– invalidity of charge, and why liquidator would try to prove invalidity?

Its bit confusing.

What Im guessing is
– liquidator proving invalidity hence the charge wont classed fixed or floating,
– and it doesnt get any priority in asset distribution in liquidation
– and goes to other category for this, thus it goes in favor of issuer or company

Kindly answer my this confusion, I look forward to it, and would really appreciate your help.

Thanks Sir!