The problem is as follows:
Minimal environment:
wrong display, and will report an error Double Super Script...
The correct display result after modification
original code
\documentclass{
IEEEtran}
\usepackage{
amsmath}
\begin{
document}
\begin{
equation}
{
\tilde{
\boldsymbol{
\theta}}^{
t}}^{
\mathrm{
H}}
\end{
equation}
\end{
document}
modified code
\documentclass{
IEEEtran}
\usepackage{
amsmath}
\begin{
document}
\begin{
equation}
{
{
}\tilde{
\boldsymbol{
\theta}}^{
t}}^{
\mathrm{
H}}
\end{
equation}
\end{
document}
The difference is that {} is added inside
I am not sure why this modification is correct, and I will check the manual further to confirm