Hello, I am applying the 2013 shock dated difference-in-differences method for the model covering a period between 2012-2015. I received advice from my supervisor to limit the research period to 2012-2013 in order to conduct a robustness check and reduce noise. However, as a result of my analysis (attached results below) for the period of one year pre-and-post period data (the data for year 2012 take "0" and "1" for year 2013), my main independent variable was omitted. I am wondering that what is the reason for this and is there any way to fix it (collinearity problem)?
Thank you for your help in advance.

Code:

reghdfe logloan did logSize_wl1 TRBCapital_wl1 Crcapital_w CoreTier1_wl1 Deposits_wl1 Capital_wl1 ROE_wl1 ROA_wl1 NPL_wl1 , absorb (bank county year) vce(cluster bank)
(dropped 337 singleton observations)
(MWFE estimator converged in 104 iterations)
note: didbankcounty omitted because of collinearity

HDFE Linear regression                            Number of obs   =     10,498
Absorbing 3 HDFE groups                           F(   9,   5248) =       1.09
Statistics robust to heteroskedasticity           Prob > F        =     0.3688
                                                  R-squared       =     0.9637
                                                  Adj R-squared   =     0.9117
                                                  Within R-sq.    =     0.0016
Number of clusters (bank)    =      5,249         Root MSE        =     0.3646

                                 (Std. Err. adjusted for 5,249 clusters in bank)
--------------------------------------------------------------------------------
               |               Robust
       logloan |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
---------------+----------------------------------------------------------------
           did |          0  (omitted)
   logSize_wl1 |   .0123584   .0222295     0.56   0.578    -.0312206    .0559374
TRBCapital_wl1 |   .0347522   .0225094     1.54   0.123    -.0093756    .0788801
   Crcapital_w |   .0056442   .0069997     0.81   0.420    -.0080781    .0193665
 CoreTier1_wl1 |  -.0364985   .0225394    -1.62   0.105    -.0806851    .0076881
  Deposits_wl1 |  -.0027777   .0017416    -1.59   0.111     -.006192    .0006365
   Capital_wl1 |  -.0062382   .0076787    -0.81   0.417    -.0212917    .0088153
       ROE_wl1 |  -.0012568   .0014703    -0.85   0.393    -.0041392    .0016257
       ROA_wl1 |   .0086892   .0151252     0.57   0.566    -.0209625     .038341
       NPL_wl1 |  -.0023228   .0030787    -0.75   0.451    -.0083582    .0037127
         _cons |   9.615188   .3370406    28.53   0.000     8.954448    10.27593
--------------------------------------------------------------------------------

Absorbed degrees of freedom:
-----------------------------------------------------+
 Absorbed FE | Categories  - Redundant  = Num. Coefs |
-------------+---------------------------------------|
        bank |      5249        5249           0    *|
      county |       921           0         921     |
        year |         2           1           1     |
-----------------------------------------------------+
* = FE nested within cluster; treated as redundant for DoF computation