IW And–type dwarf novae, recognized as anomalous Z Cam–type stars, repeat quasi-standstills with damped oscillations that are terminated by small brightenings.
In \cite{kim20tiltdiskmodel}, we simulated the thermal-viscous instability with variable outer disk radius and investigated the time evolution of the instability in the tilted accretion disk.
The light curve reproduced by our simulations for the disk having relatively high tilt angles includes the three states: a small brightening, a mid-brightness interval with oscillations, and a luminosity dip, and was similar to the IW And-type phenomenon.
Also, the light curves change with different tilt angles despite constant mass transfer rates, which can naturally explain why some dwarf novae temporarily show the IW And phenomenon.
We next analyzed the {\it Kepler} light curve of KIC 9406652, a particular IW And star in \cite{kim20kic940}, and found that the negative-superhump frequency slowly increased during quasi-standstills.
However, our proposed model predicted the opposite trend.
Simulated negative-superhump frequencies gradually decrease during quasi-standstills, which reflects that the disk radius slowly shrinks.
Also, the estimated tilt angle from super-orbital signals was always less than 3~deg, the light curve profile of negative superhumps had a rich variety, and negative superhumps temporarily disappeared during the IW And state.
Although the thermal instability in the tilted disk could be a good model for a part of the IW And-type phenomenon, we have to improve the model to solve the discrepancy between observations and simulations.
In this article, I introduce our work, organize the requirements from recent observations, and discuss what is lacking in our proposed model.