Lavaan CFA, Why Only X # Cases Used and How to Control It?

I am a very green novice R user trying to do CFA with the lavaan package.

I'm having an issue with the number of observations it uses for the CFA, I'm already filtering for those who pass the attention check, but it's using less than the total number in my filtered subset.

When I run the CFA, the dataset I'm using has 309 cases/observations which have passed the attention check, but the CFA only uses 260. It displays "Number of observations, Used: 260. Total: 309

Why is this? How do I force it to run the CFA with all of them?"

Here is the code I'm using:

Filter
NLEVALID = RC_AND_MEANS_NLE_Scale_Validation %>% filter(NLE_37_ATTN_CHK==1)

CFA
model<-'
+EXT=~NLE_1_LUMINOSITY_1+NLE_7_LUMINOSITY_2_REV+NLE_13_LUMINOSITY_3
+AFF=~NLE_3_AFFECT_1+NLE_4_AFFECT_2+NLE_9_AFFECT_3+NLE_10_AFFECT_4+NLE_15_AFFECT_5+NLE_16_AFFECT_6

  • NOE=~NLE_2_NOETIC_1+NLE_8_NOETIC_2+NLE_14_NOETIC_3
  • UNI=~NLE_6_UNITIVE_1+NLE_12_UNITIVE_2+NLE_18_UNITIVE_3
  • VIT=~NLE_5_VITAL_1+NLE_11_VITAL_2+NLE_17_VITAL_3
    +LUC=~NLE_24_LUCIDITY_1+NLE_30_LUCUDITY_2+NLE_36_LUCIDITY_3
  • SIG=~NLE_19_SIGNIFICANT_1+NLE_31_SIGNIFICANT_2_REV
    +INT=~NLE_20_INTROVERTIVE_1+NLE_26_INTROVERTIVE_2+NLE_32_INTROVERTIVE_3+NLE_39_INTROVERTIVE_4
    +EXT=~NLE_23_EXTROVERTIVE_1+NLE_29_EXTROVERTIVE_2+NLE_35_EXTROVERTIVE_3+NLE_42_EXTROVERTIVE_4
    +THE=~NLE_22_THEISTIC_1+NLE_28_THEISTIC_2+NLE_34_THEISTIC_3_REV+NLE_41_THEISTIC_4
  • RAT=~NLE_21_REL_ATT_1+NLE_33_REL_ATT_2+NLE_45_REL_ATT_3
    +AAT=~NLE_27_AREL_ATT_1+NLE_40_AREL_ATT_2+NLE_44_AREL_ATT_3
    +TRA=~NLE_25_TRANSFORM_1+NLE_38_TRANSFORM_2+NLE_43_TRANSFORM_3
  • '

fit<-cfa(model,data=NLEVALID)
summary(fit,fit.measures=TRUE,standardized=TRUE)

Thanks