TXB0104-Q1: Cannot be pulled low

We used TXB0104-Q1 as a signal level shift between SOC and MCU.
There is a signal "PS" which is sent from SOC to MCU.

Now we try to pull low this signal "PS" in SOC, but it cannot be pulled low.
At the A2 pin of TXB0104, we measured this signal and the voltage dropped from 1.8V to 1.6V.

Then we removed R4290 try to pull low this signal "PS" in SOC again and found that the "PS" signal can be pulled low.

We want to know what countermeasure should be taken so that the "PS" signal can also be pulled low without removing R4290.

And could you tell me why the "PS" signal can't be pull low

Alice：

您好，

      请描述一下SOC中的PS是什么信号？下面截图是芯片对输入口的要求。