Ruling on the zakah of invested capital and its doubtful profits and return

The question: Our brother Abdulaziz al-Sudais says: I invested a sum in a real estate partnership. It made a profit at the beginning, so I left the capital and its profit in place, hoping it would make a profit again. However, the second partnership resulted in a loss. The capital is now in doubt regarding its safety and its return. Does he owe zakah on it and its profit, or how should I handle this?
The answer: As long as the partnership is for trade, benefit, and profit, the partner owes zakah every year based on its value. He must pay zakah for the year in which there was profit according to the value of the real estate, and the year in which there was a loss and the profit diminished also has its own zakah. If in the first year the land was worth one hundred thousand, he owes zakah on one hundred thousand; two thousand and a half, which is a quarter of a tenth. If in the second year it dropped and became worth only fifty thousand, he owes zakah on the fifty thousand. It is known that a tenth of it is five thousand, and a quarter of a tenth is one thousand and two hundred and fifty, and so on. If in the second year it was forty thousand, he pays zakah on forty thousand, which is one thousand.
The point is that zakah fluctuates with the value. If the value rises, the zakah rises, and if the value falls, the zakah falls accordingly, being a quarter of a tenth. This applies to real estate and other non-real estate items intended for trade. For example, one might buy cars for trade, and they remain with him for a year intended for trade, valued at, say, one hundred thousand or more. Then their value drops because a new model appears, so their value decreases. He pays zakah on them in the second year according to their new, lower value, and so on for other items. The land, the car, and all other goods follow the same path: zakah fluctuates with the value. If it rises, the zakah rises, and if it falls, the zakah falls. Yes.
The presenter: Our brother says: The capital and the profit are in doubt regarding their return?
The Shaykh: This is different. If his sale became with a person who is delaying payment, and it is unknown whether he will pay or not, he owes no zakah until the money is delivered to him. Or if it is with a poor person who is unable to pay, he owes no zakah, according to the correct opinion, until he borrows the money and completes a lunar year with the delinquent or the one unable to pay. If he receives it, he completes a new lunar year with it, meaning.
The presenter: A new lunar year?
The Shaykh: Yes, a new one. Some scholars said: He pays for the zakah of one year. If he pays for one year, that is good. If he pays zakah for one of the past years during which the money remained with this delinquent or the one unable to pay, if he pays for one year, that is good. A group of scholars said this. Otherwise, the correct view is that he is not obligated to pay anything; he completes a new lunar year. If Allah makes it easy for him to get the money from this one unable to pay or this delinquent, he pays zakah on it anew when the lunar year has passed.
However, if the land exists but its price has dropped, and he doubts the recovery of the capital, he pays zakah on what exists. He bought it for one hundred thousand, but it is now worth only fifty thousand. Real estate has become stagnant, so he pays zakah on fifty thousand. He pays zakah on the fifty thousand that the land is worth, even if it is worth only ten thousand while he bought it for one hundred thousand. He pays zakah on the ten thousand on which the lunar year has passed while it is at this value. Yes.