Error with IRanges/GRanges object

[AlejandraPanzera]

Hello,

I am trying to create a mask collection of ranges that have low coverage.

m_low <- Mask(mask.width=220210, start=start(atxGR_subset_low),width= width(atxGR_subset_low))

And I am getting this error:
Error in S4Vectors:::stopIfProblems(.valid.NormalIRanges(x)) :
object is not normal

The object (IRanges) seems to be ok:

m_low
MaskCollection of length 1 and width 220198
masks:
maskedwidth maskedratio active
1 5139 0.02333809 TRUE

and so the GRanges object 'atxGR_subset_low' (GRanges object with 6136 ranges and 0 metadata columns).

The one time I got this same error before (and I was able to fix it), is when my object had 0-based coordinates instead of 1-based coordinates (I subsetted that object and eliminated the first range, and that solved the problem). This object does not have that as you can see:

atxGR_subset_low
GRanges object with 6136 ranges and 0 metadata columns:
seqnames ranges strand

[1] tig00123515 1-8 *
[2] tig00123515 5508-5515 *
[3] tig00123515 5515-5521 *
[4] tig00123515 5521-5523 *
[5] tig00123515 5523-5524 *
... ... ... ...
[6132] tig00123515 216279-216284 *
[6133] tig00123515 216284-216286 *
[6134] tig00123515 216286-216289 *
[6135] tig00123515 216289-216290 *
[6136] tig00123515 216293-216299 *

---

seqinfo: 1 sequence from C.atrox genome

So I am not sure what the problem is. Hopefully you can help me. Thanks in advance!