Why do I see a new open trade in my account since the strategy provider didn’t open any new trades?

This is most probably because the strategy provider made a withdrawal from his account.

Copy-trading uses the logic of the Equity-to-Equity model to define the volume of all open trades. When a provider withdraws funds, then the system will automatically recalculate the volume of all open trades based on the new equity. 

Example:

Initially, the Strategy provider’s equity is 4,000 EUR while the Follower’s equity is 1,000 EUR.

The provider opens a trade of 400,000 units (4 lots) on EURUSD.

This trade will be copied with the following volume:

(Follower’s equity / Strategy Provider’s equity ) * Strategy Provider’s volume

(1,000 / 4,000) * 400,000 = 100,000 (1 lot)

Later on, the Strategy Provider withdraws 2,000 EUR from his account.

This will lead to a decrease in the provider’s equity and hence the volume of the existing open trade must be recalculated to meet the Equity-to-Equity logic.

The new volume for this trade is now:

(1,000 / 2,000) * 400,000 = 200,000 units (2 lots).

As a result, the system will automatically open an additional trade so that total volume on EURUSD is equal to 200,000 units.

Since originally there was a trade of 100,000 units, then a new trade of 100,000 units will be opened to meet the Equity-to-Equity ratio.