(LyX 2.3.6.1) Multiple lines in a table cell gives problems when producing PDF

Question

I have a table which has too much text to fit in the width of a page, so I did what is indicated in the lyx wiki, set a width for each cell so now I can add new lines to the table by only pressing enter. That looks pretty well on lyx's UI:

However, when displaying the pdf, it looks like this:

In summary, there are 2 problems: 1. The table (which is paragraph centered) seems to be centered related to the top left cell of the table. And the 2nd one, the table lines are mostly gone. When I create again the table without the width setting of the cells it looks again normal… Soo I am not sure what the problem could be.

Has anyone else had this issue? Any ideas on how could I resolve this?

Here is the code taken from the LaTeX output of LyX:

\begin{table}[H]
\begin{centering}
\begin{tabular*}{2cm}{@{\extracolsep{\fill}}|>{\centering}m{2.5cm}|>{\centering}m{2.5cm}|>{\centering}m{2.5cm}|>{\centering}m{2.5cm}|}
\hline 
Flowrate - air ($m^{3}/h$) & 500 & $CO_{2}$ injection coordinates (mm) & $\left(x,y\right)=\left(100,0\right)$\tabularnewline
\hline 
Flowrate - $CO_{2}$ ($L/min$) & 2 & Measurement times used (s) & 2, 4, 6 8 and 10\tabularnewline
\hline 
Packing type & A1200Y - 10 mm wall-gap & Total duration of the procedure & 25 h 28 m 03 s\tabularnewline
\hline 
\end{tabular*}
\par\end{centering}
\caption{Conditions of the measurement time determination process. \label{tab:MeasT conditions}}

\end{table}

Answer 1

• centering is not environment but command. So, you should use it on the following way:

\begin{table}[ht]
\centering
\begin{tabular} % or other tabular environment
   ...
\end{tabular}
\caption{...}
\label{...}
\end{table}

• instead of tabular* I suggest to use tabularx or tabularray (as is used in table example below)
• for chemistry formulae I suggest to use mhchem package
• Possible solution can be use of tabularray package. For its use you need to do the following
  • to document preamble add:

\usepackage[version=4]{mhchem}          % <---
\usepackage{tabularray}                 % <---
\UseTblrLibrary{siunitx}                % <---

• if some of above packages you haven't installed, please install them.

Table code is:

    \begin{table}[ht]
    \sisetup{per-mode=symbol}
\begin{tblr}{hlines, vlines,
             colspec={*{4}{X[c,t]}},
             colsep=4pt,
             rowsep=4pt}
% table body
Flow rate - air (\si{\meter\cubic\per\hour})
    &   500 &   \ce{CO2} injection coordinates (\si{\milli\meter})
                &   $(x,y)=(100,0)$     \\
Flowrate - \ce{CO2} (\si{\litre\per\hour})
    & 2 & Measurement times used (\si{\second}) 
            & 2, 4, 6 8 and 10          \\
Packing type
    &   A1200Y - \SI{10}{\milli\meter} wall-gap
            &   Total duration of the procedure
                &   \SI{25}{\hour} \SI{28}{\minute} \SI{03}{\second}   \\
    \end{tblr}
\caption{Conditions of the measurement time determination process.} 
\label{tab:MeasT conditions}
    \end{table}

Off-topic: caption of tables are usually above table ...